February 11, 2022

Last Updated: September 8, 2023

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The Best Reverse Osmosis Systems for Your Home

By trk

Last Updated: September 8, 2023

reverse osmosis, RO, RO filters, water filters

Our research into nonstick cookware led us to discover the importance of filtered water. PFAS--known as "forever chemicals"--are now found in nearly every water source in the world. These chemicals have been linked to numerous health issues, including cancer.

Reverse osmosis (RO) is, for most households, the most effective way to get safe, clean drinking water. In this review, we'll look at what reverse osmosis is, why it's effective, and why it's a smart choice. Then we'll review our favorite brands of all the RO options. We'll give you all the information you need to buy the best reverse osmosis system for your home.

Table Of Contents (click to open)

Best Reverse Osmosis Systems at a Glance

Here's a quick look at the best RO systems in several categories. We look at a few other less popular systems below: whole-house and outdoor RO.

RO System



APEC ROES-50 Reverse Osmosis Filter System

-Made in US

-Removes 99% of contaminants

-5 stage filter

-Silent operation

-Pre-RO filters last up to 1 year

-Works with 3/8" or 1/2" fittings

-Quick-connect fittings and color-coded tubing for easy installation

-Max 50 gpd

-Low-priced filters

-1 year warranty or 2 years w/registration.

-No remineralization

-3:1 ratio of water waste (up to 5:1 if pressure is low)

-Filter changes are a little messy

-50 GPD a little low (though s/b plenty for most families)

-Water pressure at faucet isn't great.

RO System w/Best Tasting Water:

iSpring RCC7AK 

Jump to review

iSpring RCC7AK Reverse Osmosis System

-Removes 99% of contaminants

-6 stage filter (remineralization)

-Transparent 1st stage housing for easy inspection

-Quick fittings/color-coded tubing

-Max capacity 75 gallons per day

-3.2 gallon holding tank

-Water leakage alarm

-Inexpensive replacement filters

-NSF Standard 58 certified

-WQA Gold Seal Award winner

-1-year warranty/30 day money back guarantee

-Made in China.

-Shorter filter life than other systems

-Min. 3:1 ratio of waste water 

-Final filter raises pH to about 6 

-Pump can be loud

-Water pressure at faucet isn't great

-Leak detector requires battery 

-Extra filter (remineralization) means more money long term.

Best Under Sink Tankless RO/Lowest Water Waste/Easiest to Install: Waterdrop WD-G3-W

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Waterdrop WD-G3-W Tankless Reverse Osmosis System

-Removes 99% of contaminants

-7-stage system w/just 3 filters

-Water waste as low as 1:3 

-Takes up less room without tank

-Lights indicate filter changes

-Real timeTDS indicator

-Leak detector

-Automatic flushing w/inactivity

-Easy to install

-Easy filter replacement

-NSF 58 certified: 94% TDS 

-NSF 372 certified: lead-free

-Max capacity 400 gpd

-1 year warranty/30 money back guarantee

-Made in China.

-Must drain water for 80-100s to reduce TDS

-Low water pressure w/out tank

-Requires electricity

-Not for use w/refrigerator

-TDS meter not always accurate

-Pump can be noisy


Best Budget RO System:

Express Water R05DX Reverse Osmosis System

-Removes 99% of contaminants

-5 Stage system

-Easy to install (color-coded)

-Leak detector

-Works with 3/8" or 1/2" fittings

-Max capacity 50 gpd

-4 gallon tank (3.2gal capacity)

-NSF certified 42, 58, 401

-Extra filters included

-Customizable w/UV filter, alkaline filter, deionization filter, and more

-Excellent customer service

-1 year warranty.

-High waste water ratio (3:1, more if pressure is low)

-Filters don't last as long as some other brands

-No remineralization

-As is, not great for well water

-At least some parts made in China.

Best RO System for Well Water/Low Water Pressure: 

iSpring RCC1UP-AK

Jump to review

iSpring RCC1UP-AK Reverse Osmosis System

-Removes 99% of contaminants

-7 Stage system

-Built-in booster pump

-UV filter for pathogens (for well water)

-2:1/1:1 waste water ratio

-Transparent 1st stage housing for easy inspection

-3.2 gallon tank (2.5gal capacity)

-100 gpd max capacity

-Quick fittings/color-coded tubing

-Big and heavy, may not fit under sink

-Electricity needed for UV lamp

-May not need booster pump 

-May not need UV lamp (best for well water)

-Made in China.

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Why Filter Your Water (Do You Really Need an RO System)?

You probably know about common contaminants in water like lead, arsenic, fluoride, chlorine, and chloramine. Even most inexpensive faucet and filter pitchers can get out most of these. 

So why spend money on an expensive RO system?

Because there are literally thousands of chemicals that can contaminate your water. And the EPA requires municipalities to test for only about 90 of them. PFAS--the chemical family that contains PTFE (Teflon), PFOA, and the new GenX replacement for PFOA--has more than 5,000 chemicals that are used across dozens of industries, and the EPA doesn't require testing for any of them. In fact, there aren't even any regulations about dumping these chemicals into local water supplies. Companies like Dupont and 3M have been dumping them with impunity for more than 50 years.

For this reason, nearly every water supply on the planet now contains traces of PFAS. And more than 90% of Americans have PFAS in their body. These chemicals don't break down easily--thus their nickname "forever chemicals"--and have been linked to several health issues, including some cancers.

We learned about PFAS when we researched nonstick cookware. What we found out was alarming: you are more likely to ingest PFAS from your drinking water than from your nonstick cookware. 

And this is just one industry! People are starting to wake up to the dangers of PFAS, but there are thousands of unregulated chemicals that aren't on anyone's radar and probably aren't being regulated by the EPA. Industrial waste, agricultural runoff, pharmaceuticals, and radioactive particles are just a few of the categories that could be lurking in your water. 

We are not alarmists, and we don't want to scare anyone. But facts are facts. And the world's water supplies are full of potentially harmful contaminants.

Thus, if you want safe, clean, healthy drinking water, you need to filter it. You can't depend on your municipality, or the EPA, to provide you with a safe source of water.

Reverse osmosis is the best filtration system available. It not only gets out the stuff you know about; it gets out all the stuff you don't know about.

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What Is Reverse Osmosis? A Quick Overview

How Reverse Osmosis Works Diagram

diagram from espwaterproducts.com

Reverse osmosis is one of the safest and most effective water filtration methods available. It's actually a very simple process that involves "pushing" water through a membrane which has pores small enough to basically let only water pass through. The pushing is from your water pressure, and no electricity is required unless you need to add a pump or pressure regulator to control the water pressure.

The pores in the RO membrane are typically 0.0001 micron, which is smaller than a salt (NaCl) molecule. Very few materials can pass through these extremely tiny pores. The pores can be as large as 0.001 microns, which is still extremely small. The smaller the pores, the more pressure required to push the water through--but smaller pores also means better filtration. 

The contaminated water left behind is discharged into your drain system. Or, you can capture it and use it for non-drinking purposes such as watering your house plants (but not a vegetable garden).

Of course, there's a bit more to it, which you can read about here if you're curious. But overall, it's a pretty simple system.

An entire RO system has much more than the RO membrane, however. We explain how the whole system functions below in How Does a Reverse Osmosis System Work?

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Why Is Reverse Osmosis the Best Water Filtration System?

Reverse osmosis is the most comprehensive water filtration system available. The RO membrane, along with the pre-filters and post-filters, remove the highest number of contaminants from your water.

The reason this is important is that even if you're primarily concerned about common contaminants like lead, arsenic, fluoride, and chloramine, which even many pitcher filters can remove, there are literally thousands of contaminants that could be in your water. PFAS are an excellent example (which we wrote about above and in this article about nonstick cookware chemicals). 

There are dozens of categories of contaminants that aren't even tested for in municipal water supplies: PFAS and thousands of other organic compounds, pharmaceuticals, radioactive materials, agricultural runoff, industrial waste, and so much more.

With an RO system, you can be assured that everything is removed; not just what the EPA tests for. 

The only other system that can do this is distillation, which usually can't produce enough water for a family of 2 or more people (most distillations systems produce a gallon at a time and take about 8 hours to do so).

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What Can't Reverse Osmosis Remove?

As great as RO is, it can't remove everything.

Reverse osmosis can not remove most organic compounds, bacterial microorganisms, chlorine and chlorine by-products, chloramine, and dissolved gases like carbon dioxide, methane, and radon. It can also not remove some pharmaceuticals, or Splenda. 

This is why an RO system has pre-filters. These remove the contaminants that the RO membrane can't, such as chlorine and chloramine. When you put them all together, you have the most comprehensive water filtration system available. 

It can be a little confusing: though RO can't remove some things, the other filters in the RO system do. So when manufacturers say, for example, that an RO system removes chlorine, they are speaking about the system as a whole and not the RO membrane. 

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How Does a Reverse Osmosis System Work?

Reverse osmosis is actually a very simple process: it pushes water through a semipermeable membrane that allows the water to pass but blocks dissolved compounds that are larger than the pore size, usually 0.001-0.0001 microns. (A micron, also called a micrometer, is one-millionth of a meter, so we're talking small.)

RO removes up to 99% of thousands of chemicals, including fluoride, lead, nitrates, sulfates, salts, pesticides, detergents, most radioactive compounds, PFAS (the dreaded "forever" chemicals found in nonstick cookware), and thousands more. 

Because the system works by pressure, the process doesn't require a power source--unless your water pressure is so low that you need a pump to boost it. 

There's more to an RO system than the RO membrane, however. Other components of an RO system include filters, the storage tank (although some systems are tankless), faucet, and, optionally, a permeate, booster pump, or a pressure regulator. 


APEC ROES-50 replacement filters

Typical filter change set for an RO system: pre-filters, RO membrane, and post-filter.

Typically, RO systems typically have 4 or 5 filtration stages that purify your water. These include pre-filters, the RO membrane, and post-filters. Systems can also have an optional remineralization filter which adds healthy minerals back into the water, and an optional UV lamp to kill pathogens (essential for well water). Both remineralization and the UV lamp are considered "filtration" phases.  

Here are all the filters you can find on an RO system (note that some are optional):

  1. Sediment pre-filter: Removes soil, rust, sand, dust, and other large particles.
  2. Carbon pre-filters: Removes tap water disinfectants (i.e., chlorine and chloramine), organic compounds including VOCs, unpleasant odors and tastes, some heavy metals, and a few other chemicals the RO membrane can't remove. A carbon filter can contain activated carbon or catalytic carbon. Catalytic carbon is the most effective type and can remove several harmful contaminants including chloramine (which an RO membrane cannot remove).
  3. Granular carbon pre-filters: Same as the carbon pre-filter. Most systems have both types of carbon pre-filters. Some just have one, or one that combines characteristics of both.
  4. Reverse osmosis membrane: The heart of the system. Removes most remaining contaminants such as  sodium, chloride, copper, chromium, lead, radiation, PFAS, and more; it will also greatly reduce arsenic, fluoride, radium, sulfate, calcium, magnesium, potassium, nitrate, and phosphorous (most more than 90%).
  5. Post-filter: Another carbon filter that  removes any residual bad tastes and odors to ensure your water tastes and smells good.
  6. Remineralization filter: (optional) This filter actually adds healthy minerals back into the RO water, raising the pH level and in some cases improving the taste. If you're concerned about not getting enough minerals in your diet, get an RO system with a remineralization filter (or just add these drops to your RO water).
  7. UV lamp: (optional) RO removes some pathogens, but bacteria and some others are too small. If you have well water or are for some other reason concerned about pathogens, you want a system with a UV lamp to ensure all pathogens are removed from the water.

Unless you want remineralization or need a UV lamp to kill pathogens, a 5-stage system is all you need to have the cleanest, safest drinking water available.

Storage Tank

RO storage tank

Most reverse osmosis systems have a water storage tank which holds 3-4 gallons of water (many brands also have larger tanks available that you can buy separately). The tank has a pressurized bladder made of food-grade rubber that provides water pressure to the faucet. Tanks also have an automatic shut-off valve that stops the filtration process when the tank is full. It's a fairly elegant system, especially when you realize it works on pressure, with no electricity required.


Express RO5D faucet

RO systems come with a faucet which you have to install on your kitchen (or bathroom) sink. This is probably the hardest part of RO system installation as it requires you to drill a fairly large hole in your sink. Most brands provide excellent instructions and videos for doing this.

Do note that the water pressure of your RO faucet probably won't be great. This is just the nature of RO and something you'll learn to live with. Pumps can boost the pressure, and tankless systems are usually a little better, but you're never going to get fast gushing water from an RO faucet. 

Pumps and Pressure Regulators

You can use a permeate pump, booster pump, or pressure regulator to control your water pressure and maximize the efficiency of your RO system. In general, if your water pressure is below about 40psi, you should use a pump to increase it. If your water pressure is above about 70psi, you should use a pressure regulator to decrease it.

How do you know what your water pressure is? You can buy an inexpensive gauge to test it. This gauge is made specifically to test RO systems. Or, if you want one you can use to test your water pressure at different outlets in your home, this gauge comes with several fittings.

Permeate Pump

Aquatec ERP 500 Permeate Pump

A permeate pump boosts the water pressure going into your RO system and can greatly improve the waste water ratio. It requires no electricity and works by storing up water to increase the pressure against the RO membrane. 

Booster Pump (Electric)

iSpring Booster Pump

Electric pressure pumps also lower the amount of water waste while boosting overall water production. They use electricity to pump water through the RO system at the most efficient pressure level.

Pressure Regulator

Reverse Osmosis Pressure Regulator

A pressure regulator does the opposite: it reduces water pressure if your incoming water pressure is too high, typically more than 70psi or so. Too-high pressure will cause a lot of wear and tear on your system and can result in leaks and other issues, so it is just as important to decrease high water pressure as it is to increase low water pressure.

In general, if your water pressure is below about 40psi, you should use a pump to increase it. If your water pressure is above about 70psi, you should use a pressure regulator to control it. Check the specs on your RO system for exact numbers.

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Tank Vs Tankless Reverse Osmosis: Which Is Better?

In this review, we are looking only at under-sink reverse osmosis systems. They are the most popular type and what most people want in their homes. 

There are two types of under sink RO systems: tank and tankless. Before you decide which one you want, you should know all the details. 


APEC ROES-50 Reverse Osmosis Filter System


Systems with tanks store up a supply of filtered water, usually 3-4 gallons (with many brands offering larger tanks sold separately), so you have a ready supply at the faucet. This uses natural water pressure to push water through the RO system and no electricity is required. 

Tanks have an automatic shutoff valve that stops the water flow when full and starts it again when you've used water from the tank. Unless you are draining the entire tank at one time, you should always have a ready supply of clean, filtered RO water.

Tank RO systems are also quite reasonably priced. You can get a complete system for less than $200; our budget choice is about $150 and is a complete system.


There are a couple of drawbacks with a tank. The biggest one for most people is that the water pressure at the RO faucet is pretty weak, so it takes awhile to fill a pot for, say, pasta, or even a glass. And as the tank is depleted, the flow gets slower and slower. However, it is not un-usably slow, probably taking less than two minutes for pasta water and about 10-15 seconds for a glass. (This may not sound like a long time but compared to the flow of your unfiltered water, it is.)

Another drawback is the the tank takes up a lot of space. If you have an RO system under your kitchen sink, you won't have a lot of room for other things. 

Yet another drawback, albeit a minor one, is that tank RO systems have a smaller gallons-per-day capacity than tankless systems. This is minor, though, because even the lowest capacities produce plenty for most families--for example, 50gpd is plenty of drinking and cooking water for a family of four (or more).


Waterdrop WD-G3-W Tankless Reverse Osmosis System

Tankless systems have an electric pump that pushes water through the RO system when you turn on the faucet to get water. For this reason, tankless systems always require an electric hookup. 


The smaller footprint of the tankless system is its main appeal for many people. If you have limited space, a tankless system may be the best choice for you. 

They also look much nicer than the tank systems, typically having all the filters in an enclosed case--but since it goes under your sink--out of sight--this shouldn't be much of a selling point.

Another advantage of tankless systems is that they can produce a lot more water in a day, primarily because of the electric pump. For example, a tank system typically has a capacity of less than 100gpd, while a tankless system can have a capacity around 400gpd.

Because tankless systems are hooked up to electricity, they often have indicator lights for TDS (which may not be accurate) and filter changes, which is convenient. They can also have built-in leak detectors which will sound an alarm if moisture is detected around the unit. (Many tank systems also have leak detectors which usually run on a battery.)

Also, tankless systems have the reputation of having better faucet flow. However, the flow is typically only slightly better than tank RO systems; if you've had both, you probably won't notice much of a difference. (You'd think with the much higher daily capacity that the flow would be much stronger, but it isn't.)


The need for electricity can make tankless RO systems more complicated to install. And some of the pumps are loud (which can be annoying if you're accustomed to the complete silence of a tank RO system). 

Tankless RO systems are also quite a bit more expensive than tank systems. You can get a complete tank RO system for less than $200; a tankless system will run you about $400.

Probably the biggest drawback of a tankless RO system is the TDS issue. Because there isn't a ready supply of filtered water, you have to run the faucet for up to 2 minutes (maybe more) to get an acceptably low rate of TDS. This means running a gallon or more of water down the drain, not to mention having to wait for clean water. And this is the case every time the system has been unused for even just an hour or so. 

(If you have a tankless system, it would be a good idea to buy a TDS meter and test it to see exactly how long you need to let it run to get clean water. Manufacturers do not always disclose this issue.) 

Our Recommendation

If you have the room, an RO system with a tank is the way to go. Tankless systems have a lot of nice features, but the high TDS output is a serious issue. Yes, tanks take up more room and yes, the water pressure isn't as good, but overall, it's the better system (and probably the easier one to install, especially if you're not particularly handy or need to put a power outlet in under the sink). 

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Pros and Cons of Reverse Osmosis Systems

Here's a summary of the pros and cons of reverse osmosis:



Most comprehensive filtration system

Removes even healthy minerals

Environmentally friendly 

Require maintenance every 6-12 months

Reduces plastic (water bottle) waste

Can waste a lot of water

Many systems require no electricity

Low water pressure from RO faucet

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What to Consider When Buying an RO System

If you want to put in an RO system, or even if you hire a plumber to do it for you, there are several important considerations (not just tank vs. tankless). Here we take a look at the important features you should think about before buying/installing.

Plumbing Requirements

Start by inspecting the space under your sink. Is there room for an RO system? If you have a garbage disposal, it may be challenging to fit a reverse osmosis system below the sink.

RO systems require their own faucet, so you’ll have to install a second faucet at your sink, either by drilling through the sink edge or the countertop. 

RO systems use either an air gap or non-air gap faucet. They remove impurities by separating them from your clean water supply and discharging the contaminated water. That water must be drained through an air gap that drips into a tube connected to the sink drain. An air gap faucet prevents the dirty water from being drawn back into the system’s discharge side.  

If the faucet is not near the RO system and is therefore not sharing a discharge line, there is no need for an air gap faucet. Otherwise, purchase a system with an air gap faucet. 

Ease of Installation

Most RO systems are fairly easy to install, if you're handy and own all the tools and equipment to install them. All the brands we recommend have good installation guides as well as videos and live support to help you through the process. They also all use standard connector sizes, which may not be the case if you try to save a few bucks and go with a budget brand--this will mean at least one trip to the hardware store for adapter fittings.

If you're not handy, don't own a drill, or don't want to undertake the installation yourself, you can hire a plumber to do it for you. It should take less than two hours. 

Tank Size

If you're buying a tank RO system, you should look at the tank size before buying for two reasons.

One, will the tank fit under your sink? 

Two, is the tank large enough to provide a ready supply of drinking and cooking water for your entire family?

Most tank systems come. with 3-4 gallon tanks that hold about 

Water Output (Flow Rate)

Here, we're looking at two things: 1) the maximum number of gallons a system can produce in a day, and 2) the water pressure at the faucet.

Maximum Daily Output

Tankless systems win here, producing much more water and faster water flow. But even with their much higher daily capacity, the faucet flow is still slow, at least compared to your unfiltered water. 

And tank systems, though they have a considerably lower daily capacity, produce plenty of drinking and cooking water for most families; if you need more than 50 gallons of clean water per day, you need a commercial system. 

So, you should look at the daily capacity of a system, because they can vary quite a bit. But unless you're using huge amounts of filtered water, most RO systems will produce enough.

Faucet Flow Rate/Water Pressure

Before you buy an RO system, know that water pressure won't be great no matter which kind of system you buy. Because of the filtration process, it's going to be much slower than the water at your sink for both types of systems. So if you don't have the patience to wait a couple of minutes to fill a pot, or several seconds to fill a glass, RO may not be the right choice for you.

However, even though the flow is slow, you'll get used to it. In general, it will take less than half a minute to fill a large glass, and about two-three minutes to fill a pasta pot. If you're filling something bigger, you can do other tasks while you wait. You get used to it and it isn't a big deal.

It's a small price to pay for clean, healthy water.

Waste Water

No matter how efficient an RO system is, it's going to produce waste water. All RO systems create waste water; it's the water that contains the filtered-out contaminants and goes down the drain (or captured for watering house plants and other non-potable uses). 

Many RO systems are incredibly inefficient. They can create 3-5 gallons of waste water for every 1 gallon of filtered water. A number of factors affect this ratio, including the concentration of contaminants in the water, water temperature, and water pressure: lower contaminant concentration, higher water temperature, and higher water pressure all result in less waste water for each gallon of filtered water. 

Tankless systems are more efficient, often boasting a waste water ratio as low as 1:1. But the ratio is often higher than this. And because of the TDS issue--you have to let a gallon or more run down the drain before the TDS reaches acceptable levels--you still end up wasting a lot of water. 

Some countertop RO systems have an incredibly low waste water ratio. If this is a primary concern, you may want to look into a system like the Aquatru.

How to Improve Your Waste Water Ratio: You can't change the contaminant level in your water, and you probably can't do much about water temperature (but never, ever hook an RO system up to hot water). However, you can make sure that the water pressure is within the specifications of your RO unit. Typically, this means between 40psi and 70psi, with 60psi usually considered ideal. 

If your water pressure is low, you should use a permeate or booster pump to increase it. If your water pressure is high, you should use a pressure regulator to lower it. (We talk about these above in the Pumps and Pressure Regulators section.)

You can also capture the waste water and use it for non-drinking and non-cooking purposes, like watering house plants; don't use it on a vegetable garden or give it to your pets.

Number of Filters and Filter Life

Filter changes are the primary maintenance required with an RO system. Systems can have as few as three filters or as many as six. If there's a UV lamp, that also requires periodic changing.

Each system will have a recommended schedule for filter changes, but you should test your own water for TDS to determine when you need to change filters because you may need to do it more often than the recommended schedule. If your TDS level is high, your water has an off taste, or the flow has slowed down, it's probably time to change filters. 

Filters need to be changed at different frequencies. The pre- and post-filters typically need to be changed every 6-12 months, while the RO membrane will last for 2-3 years.

Different brands offer different filter packages and the costs vary. Some brands last longer than others, while shorter-lived filters may be considerably less expensive. And of course, you need to consider how many filters you want to deal with as a whole, because more filters means more long-term maintenance and expense (and they may not add a lot to the system). 

We include the annual filter cost (approximate, of course, depending on your water) for each brand we review and recommend. In general, expect to spend about $100 annually for filter changes. 

About Filter Availability

You may see comments about lack of filter availability for several RO systems. This is because of supply chain issues and NOT because the companies have stopped making filters. We recommend that when you buy an RO system, verify with the manufacturer that they do still have filters for your model, and buy 2-3 years supply of replacement filters if you can. 

Filter Changing

You may also want to consider how easy it is to change the filters in the system you buy.

If you install it yourself, then filter changes should be a breeze. Companies also have excellent instructions, videos, and live support to help you. 

Some systems have messy filter change procedures in which you have to have a bucket to catch the water that gushes out when you open the system. 

It shouldn't be a huge concern, but you should understand what's involved in filter changes before you buy an RO system.

Can It Connect to a Refrigerator?

Almost all tank systems have an inexpensive kit (less than $30) that you can connect to your refrigerator's ice maker and/or water dispenser. If you use your refrigerator to make ice or for drinking water, this is well worth doing.

Not all tankless systems have this option. The Waterdrop G3, which is our recommended tankless system, doesn't have the option to hook up to a fridge. 

We include refrigerator kit information for all the brands we review below.

NSF Certification

Some RO systems are certified by the NSF/ANSI and the WQA. These acronyms stand for "National Sanitation Foundation," "American National Standards Institute," and the "Water Quality Association."

These organizations do independent testing and certifications for drinking water systems. There are a number of certifications RO systems can have. The most popular are:

NSF 58: Ensures the RO system removes 94% or more of TDS (total dissolved solids)

NSF/ANSI 372: Certifies that all parts of an RO system are lead-free.

You can read more about water certifications in this very detailed document from the NSF.

Certifications are good, but they aren't essential. Many high quality systems don't have any certifications, or only partial certification. 

The reason certifications aren't all that important is that all RO systems work pretty much the same way. The pre-filters, post-filters, and RO membrane are all going to do pretty much the same thing whether they're certified or not. 

Also, you can test your water yourself for TDS. If the TDS rate is low, you know the system is doing its job.

If certifications give you peace of mind, you should get a system that has them. All of our recommended models have at least some certifications.

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Best Overall Reverse Osmosis System: APEC ROES 50 Essence 5 Stage RO System

APEC ROES-50 Reverse Osmosis Filter System

See APEC ROES 50 Essence Series on Amazon

About $200

Features and Overview

What We Like: This is a no-frills, yet complete RO system that gets excellent reviews. The APEC Essence ROES-50 will remove up to 99% of contaminants, including chlorine, VOCs, fluoride, arsenic, lead, nitrates, radium, heavy metals and 1000+ contaminants. The system is WQA certified to perform as stated.

One of its best features is its long-lasting, low-cost replacement filters, which will save you a lot in the long run: annual filter cost will run you less than $40, plus an RO filter every 2-3 years. 

The quick-connect fittings, color-coded tubing, and excellent installation documentation and videos make this an easy system to install if you are a DIY-er and have the right tools; if you aren't, you may find prefer to hire a plumber--it should take less than two hours to install.

The "designer" faucet is lead-free (as should be the case for all RO systems), with a brushed stainless exterior. It's a little flimsy, but this is the case for all RO systems we looked at.

Refrigerator Hookup Kit: You can run this RO system to your refrigerator water dispenser and ice maker. This kit is sold separately for about $18. Note that the tank has to be full to have adequate pressure to make ice/dispense water.

APEC ROES-50 Icemaker Kit

APEC Water Systems ICEMAKER-KIT-RO-1-4.

Finally, the APEC Essence ROES-50 is designed and assembled in the USA; filters probably come from overseas.

What We Don't Like: The system is not modular (like some more expensive RO systems), so filter changes are wet. It's a small drawback, but besides dealing with the water, an easy job.

The APEC ROES-50 is not NSF/ANSI certified for lead and organic contaminant removal. However, testing shows it removes 99% of both lead and organic contaminants (so as good as certified filters). 

Also, some of the plastic parts might feel cheap to you. When installing, you have to be careful not to over tighten or you can crack the plastic. 

Upgrade: APEC Ultimate RO-PERM (about $360): Comes with permeate pump to boost water pressure and unit and filters are WQA certified. Permeate pump can reduce water waste up to 80% if you have pressure lower than 40psi. (You can also add a permeate pump to the ROES-50.)

Ease of Installation

As we said, ease of installation is based on your experience and having the right tools, which include a drill and the right drill bits, Phillips screwdriver, wrench, and teflon tape. All the rest of the parts are supplied with the system (e.g., filters, fittings, tubing, and installation guides).

This system also has a refrigerator hookup kit that is easy to install.

These documents will help you figure out installation requirements:

Installation Manual (PDF)

User Manual (PDF)

Product Documentation (PDF)

There are also several installation videos you can watch if you need more help:

Unpacking and checking the unit

Installing and fitting filter and membrane units

How to install the feed water and drain saddle adaptor

Installing the RO faucet

Connecting the tubing connections and system start up.

If you don't want to undertake it, a plumber can do it, usually in less than two hours.

Filters/Filter Changes

APEC ROES-50 replacement filters

APEC ROES-50 filter replacement set.

Annual Filter Cost: About $75

See Stage 1-3 replacement filters on Amazon (should be changed every 6-12 months depending on water)

See all APEC ROES-50 replacement filter options on Amazon

Filter changes should occur:

  • Sediment pre-filter: Every 6 to 12 months
  • Carbon block pre-filters: Every 6 to 12 months
  • RO membrane: Every 2 to 3 years for city water, 2 years on well water
  • Carbon post-filter: Every 2 to 3 years

You can get an entire set of filters for about $75; you can see above how long these will last.

Different water varies, which is why there's such a big time range for filter changes. You should use a TDS meter to check your water so you know when your filters need changing. You can also tell if the taste or quality of the water is off.

You have several buying options for APEC ROES-50 filters. The more you buy at once, the more you save. You can also choose to buy aftermarket replacement filters that are even cheaper, though they may not work as well or last as long. Or, you can upgrade to USA-made filters, but they probably won't get you much more filtration than the standard APEC filters.

You may also want new o-rings. All options for filters, o-rings, and other parts are shown here.

read apec essence roes-50 ro system reviews on amazon


Water Pressure Required: 40-85 psi
If the pressure is less than 40, a permeate pump pressure booster is required. If water pressure is above 85psi, you should install a pressure regulator.

Total Capacity: Up to 50 gallons per day based on 60 psi at normal household temps (less if pressure is lower)

Storage Tank: 4 gallons

Max TDS: 2000ppm 

Waste Water: 3-5 gal per 1 gal of filtered water; higher if water pressure is low

Number of Filters: 4 including RO membrane

Size: 16 x 5.25 x 17.5 inches (WxDxH)

Weight: 25 pounds.

Aquatec ERP 500 Permeate Pump

A permeate pump is required for water pressure lower than 40psi.

Pros and Cons

  • 99% of contaminants removed
  • Great-tasting water (even without remineralization)
  • Quick-connect fittings and color-coded lines for easy installation
  • WQA certified
  • Silent operation
  • No electricity required
  • Works with 3/8" or 1/2" fittings 
  • Low-priced filters
  • Excellent installation instructions and videos available
  • 1 year warranty or 2 years w/registration.
  • Designed and assembled in USA.
  • No remineralization
  • Filter changes can be messy (wet)
  • May have slow water pressure w/out permeate pump
  • 50 gallons per day may be low for some families
  • Takes up a lot of room under a sink
  • Certified for, but not a great choice for well water
  • Not NSF certified
  • Installation may be hard if you're not a DYI person.


For a basic RO system that removes 99% of contaminants, the APEC Essence ROES-50 is a good buy at just under $200, with affordable filters for long-term savings. It's one of APEC's lower grade systems but it is WQA certified, gets excellent reviews, and removes just as many contaminants as higher-priced RO systems.

If you have poor water pressure, a permeate pump will improve your waste water ratio, and a remineralization filter can improve water taste (but we thought this water tasted fine).

See Permeate Pump on Amazon

See Icemaker Kit on Amazon

buy apec essence roes-50 reverse osmosis system on amazon:

APEC ROES-50 Reverse Osmosis Filter System
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Best Tasting Water: iSpring RCC7AK Reverse Osmosis System

iSpring RCC7AK Reverse Osmosis System

See iSpring RCC7AK on Amazon 

About $185

Features and Overview

What We Like: Like all RO systems, the iSpring RCC7AK removes more than 1,000 impurities including arsenic, phthalates, pharmaceuticals, heavy metals, pesticides, herbicides, fluoride, VOCs, chlorine, chloramine, endocrine disruptors, viruses, protozoa, bacteria, iron, rust, and more.

Its defining feature is its 6th filter that adds minerals back to the water to improve taste and increase trace mineral consumption. (This will also increase TDS, but in a good way.)

It has a battery-operated leak detector which will sound an alarm if it detects moisture outside the system, which is a nice-but-not-necessary feature (you can easily see if your RO system is leaking). You have to remember to test and change the battery to keep the alarm functioning.

Installation is easy for anyone who is reasonably handy and has all the tools to do the job. (As with all RO systems, be sure to have teflon tape on hand to seal connections.)

The filters are reasonably priced: you can get a 2-year supply of all the filters for about $100. 

iSpring RO systems are NSF Standard 58 and WQA certified so you can rest assured that you're getting some of the best, most effective products on the market. 

Refrigerator Hookup: Yes, you can use this system on your refrigerator's ice maker and water dispenser. You can purchase an extra line for your refrigerator for about $12.

iSpring ICEK Fridge Water Line Connection Kit

iSpring Refrigerator Hookup Kit.

What We Don't Like: The extra filter makes it bigger than other RO systems, which may make it harder (or even impossible) for many to install. 

The filters don't last as long as on some other brands. Add to this that there's an extra filter to replace, and your long-term maintenance costs are going to be higher than with some other systems (though the difference is not huge). 

Also, filter changes are wet, like the APEC ROES-50 (above), but not difficult.

The brushed nickel faucet isn't the most robust design, but pretty standard for these systems.

Some users complained that components were poorly made and a number of people had leaks, though the overwhelming majority of reviewers (including us) found the system was excellent and did exactly what it was supposed to do without any fuss. We suspect leaks occur when people over-tighten the fittings and crack the pipes.

Finally, even with the remineralization, the pH levels are still low. They hover around 6, which is still acidic. Most people want their water to be alkaline, which means a pH above 7. It may depend on your source water, but you probably aren't going to reach that even with the remineralization filter.

What About the California Prop 65 Warning? This system has a California Prop 65 warning because parts of it contain PVC. iSpring assures us no PVC chemicals can leak into the RO system, but they are required to disclose it nevertheless. You can read more about it at the iSpring website

Ease of Installation

The iSpring RCC7AK is fairly. easy to install if you are a DIY-er and have the right tools. The company provides excellent documentation, plus videos, plus live support if you need it. 

There is an inexpensive kit to hook the system up to your refrigerator ice maker and/or water dispenser.

If you aren't particularly handy, you may want to hire a plumber to install it. It should take less than two hours.

Note that if your water pressure is below 40psi, you'll need a pump to boost it; if it's above 80psi, you need a pressure regulator. (See Specifications section below for links to both of these.) 

Here are some links to help you decide if you can install it yourself:

User Guide (PDF)

Product Documentation (PDF)

User Manual (PDF)

You can also find many helpful videos on iSpring's YouTube channel. Or, you can go to iSpring's website for helpful videos.

If you don't want to undertake it, a plumber can do it, usually in less than two hours.

Filters/Filter Changes

iSpring RO Replacement Filter set

iSpring replacement filter set.

Annual Filter Cost: $50 when you buy a 2-year supply for $100, including the RO membrane. Cheaper if you buy even more.

Filter changes are fairly easy, but a little messy. To change the filters or membrane, you just turn off the water and depressurize the system. Open the filter housings, remove the old filters, and replace them with new ones.

This filter change video from iSpring covers all of iSpring's RO systems. It's about 7 minutes long, easy to follow, and should be a big help in changing the filters.

Filter changes should occur:

  • Polypropylene pre-filter: Every 6-12 months
  • Granular activated carbon (GAC) pre-filter: Every 6-12 months
  • Carbon block pre-filter: Every 6-12 months
  • RO membrane: Every 2 to 3 years
  • GAC post-filter: Every 12 months
  • pH alkaline post-filter: Every 6-12 months.

iSpring has several filter buying options. Note that filters are cheaper than for the APEC ROES-50 (reviewed above), but they don't last as long and there are 6 instead of 5, so you may spend more in the long run with this system than with the APEC. Cost for 2-year supply of filters is about $100.

read reviews of iSpring rcc7ak ro system on amazon


Water Pressure Required: 45-70 psi @ 40-100F
If water pressure is lower than 45psi, this system won't work. See iSpring RCC7P-AK (with electric booster pump), or system with permeate pump (no power required). If water pressure is above 80psi, you should install a pressure regulator.

Total Capacity: Up to 75 gallons per day at 60 psi water pressure at 77F (less if water pressure is lower)

Storage Tank Capacity: 3.2 gallons (2.5 gal holding capacity)

Faucet Flow Rate: 2 minutes/gallon

Max TDS: 750ppm

Waste Water: 3 gal per 1 gal of filtered water; higher if water pressure is lower than 60psi

System Dimensions: 14.5 x 6 x 18 inches (WxDxH)

Weight: 20 pounds.

Pros and Cons

  • 99% of 1000's of contaminants removed
  • 98% of lead removed; 96% fluoride removed 
  • Great-tasting water
  • Quick-connect fittings and color-coded lines for easy installation
  • WQA and NSF 58 certified
  • Has refrigerator connection
  • No electricity required
  • Low-priced filters
  • Excellent installation instructions and videos available
  • 1 year warranty/30 day money back guarantee.
  • Faucet flow isn't very strong (2 gal/min)
  • Filter changes are wet (but not hard)
  • Filters don't last as long as some other brands
  • Remineralizer only brings pH up to about 6.0 (still acidic)
  • Takes up a lot of room under a sink
  • Tank is smaller than APEC ROES-50
  • Not a great choice for well water
  • Installation may be hard if you're not a DYI person
  • Max TDS of 750ppm is low compared to APEC-ROES-50 (2000ppm), but shouldn't be an issue for most water supplies
  • Made in China.


Overall, the iSpring RCC7AK is a great system at a great price, and it gets overwhelmingly positive reviews from users. Some people complained about leaks, but it was a very small percentage.

The faucet flow isn't great, but it's about the same as other pressurized tank RO systems. The remineralization filter may improve the taste of your water, but if you're looking for alkaline water from the sixth filter, you probably aren't going to get that. 

If you have exceptionally high TDS rates, you may want to go with a different system. This one is rated for 750ppm, while the APEC ROES-50 above is rated at 2000ppm. But for most water supplies--well or city--this shouldn't be a problem.

See iSpring ICEK Fridge Connection Line on Amazon

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iSpring RCC7AK Reverse Osmosis System
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Best Tankless Under Sink Reverse Osmosis System/Least Water Waste/Easiest to Install: Waterdrop WD-G3-W

Waterdrop WD-G3-W Tankless Reverse Osmosis System

See Waterdrop WD-G3-W on Amazon

About $500, or see the G2 for about $360 with no smart faucet and a higher waste water ratio.

Features and Overview

What We Like: We're not huge fans of tankless systems, but if that's what you want (or what you have room for), this is the one to get.

Installation is fairly easy if you're handy; drilling a hole for the faucet is probably the hardest part.

Filter changes are super easy: you just remove the filter housing from the front of the unit (shown above) and put the new one in. And though the system has 7 stages, three of them are in one filter, so there are only three total filters to change (including the RO membrane).

Indicator lights make filter changes even easier, letting you know when filters are due for a change. The G3 also has other "smart" features like automatic flushing after 24 hours of inactivity, overwork, and frequent start/stop protection. 

It also has a built-in TDS meter, so you always know (assuming the reading is accurate) what's in your water.

Water waste can be as low as 1:1, if you have enough water pressure. This is somewhat ruined by the fact that you need to let the system run for 80-100 seconds (equivalent to a gallon or more) to bring the TDS down to acceptable levels; because there's no tank that stores filtered water, you have to do this pretty much every time you use the system. 

What We Didn't Like: As we said, we're not huge fans of tankless systems, so many of the things we dislike about the Waterdrop G3 applies to all the tankless systems we know about. The first and most important is that without a tank that stores the purified water, you have to run the system for a long time before the TDS level comes down to acceptable levels: about 80-100 seconds, or close to two minutes. This wastes about a gallon of water, not to mention your time. And we also recommend you use a TDS meter to test your water so you know when it's good to drink, as it will vary depending on the water supply.

Second, even with the high capacity of 400 gpd, the flow rate is pretty slow. If you're looking for a faster faucet flow, you aren't gaining much over a tank system.

Third, the system requires electricity, which makes it a little harder to install. More importantly, it means you have no source of drinkable water if the power is out.

Fourth, tankless systems are more expensive. 

Finally--and these are exclusive to the G3, but may also apply to other tankless systems--you can't connect this unit to a refrigerator, at least not without the addition of a Waterdrop PMT Mini Pressure Tank (about $30) And the TDS meter may not be accurate. You really need to buy a separate meter to test your water and compare it to the readings on the G3.  

It's sleek and pretty and has some advantages. But for how expensive this RO system is, we don't think the technology is quite there yet.

Ease of Installation

As with most of these RO systems, the Waterdrop G3 is easy to install if you're handy and have all the tools you need. 

Waterdrop has a well-written, detailed online manual to help you with installation, plus several YouTube videos.

G3 Online Installation Manual

Here's a 4-minute video that may also be helpful.

If you don't want to undertake it, a plumber can do it, usually in less than two hours.

Filters/Filter Changes

Annual cost: About $80, plus the RO filter every 2-3 years for about $90.

As we said above, filter changes are extremely easy on the G3. You just turn the knob on the filter housing on the front of the unit, pull it out, remove the old filter and put the new one in. And though the system has 7 stages, three of them are in one filter, so there are only three total filters to change (including the RO membrane).

Purchasing filters in sets is the most economical way to get them. Here is the Waterdrop G3 replacement filter set, which is one year's worth of filters, about $80:

Waterdrop G3 Replacement Filter Set

And here is the Waterdrop G3 Reverse Osmosis filter, which goes for about $90 and needs replacing every 2-3 years:

Waterdrop G3 RO Replacement Filter

Note that you get two carbon block filters and one activated carbon filter, which is the general schedule for annual filter changes.

Here's the filter change schedule for the Waterdrop G3:

  • The pre-sediment and carbon block filters provide you with up to 6 months or 550 gallons of filtered water (2 in replacement set). Use a TDS meter to test water so you know when your filters need changeing.
  • The activated carbon filter needs replacement after 12 months or 1,100 gallons (1 in replacement set). Again, a TDS meter will tell you when your filter needs replacement.
  • Reverse osmosis filter membrane lasts 2 years or 2,200 gallons of filtered water (sold separately).

read reviews of waterdrop wd-g3-w reverse osmosis system on amazon


Water Pressure Required: 14.5-87psi @ 41-100F

Power Required: 110~120V AC

Total Capacity: Up to 400 gallons per day 

Faucet Flow Rate: 0.3 gal/minute (or 1 cup water in about 12 seconds)

Waste Water: 1 gal per 1 gal of filtered water; worse with lower water pressure

System Dimensions: 18.12 x 5.67 x 17.72 inches

Weight: 30 pounds.

Pros and Cons

  • 99% of 1000's of contaminants removed
  • Tankless design is easier to install
  • Only 3 filters to change
  • Easy filter changes (less than 30s)
  • Indicators for filter status and TDS meter
  • 400 gpd capacity
  • Waste water ratio as low as 1:1
  • NSF/ANSI 58 and 372 certified
  • Excellent installation instructions and videos available
  • 1 year warranty/30 day money back guarantee.
  • Must drain water for 80-100s to reduce TDS
  • Even with pump, water flow is slow
  • Requires electricity
  • TDS meter may not be accurate
  • Pump can be noisy
  • Too tall for some under-sink spaces
  • No refrigerator hookup
  • Not a great choice for well water
  • Installation may be hard if you're not a DYI person
  • Expensive
  • Made in China.


If you want a tankless system, the Waterdrop G3 is a good choice. However, if you have room for a tank, we recommend going with that. Tankless systems tend to have poor faucet pressure, and the lack of a tank of clean water can cause the TDS level to be extremely high, so you have to drain a full gallon (at least) before the TDS comes down to acceptable levels. Other drawbacks include no fridge hookup, requiring electricity, and a noisy pump. And before you trust the built-in TDS meter, you should verify with another one to be sure. The 1:1 waste water ratio is low, but unless you're operating under ideal conditions, it's going to be higher.

The Waterdrop G3 is a sleek system, and we love the easy filter changes, but in general, these tankless systems have a few bugs to work out before we can fully recommend them. It's also expensive.

We suggest buying only if you have limited space and can't manage a tank.

see waterdrop wd-g3-w tankless reverse osmosis system on amazon:

Waterdrop WD-G3-W Tankless Reverse Osmosis System
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Best Budget Reverse Osmosis System: Express Water R05DX

Express Water R05DX Reverse Osmosis System

See Express Water RO5DX on Amazon

About $150

Features and Overview

What We Like: The Express Water RO5DX is not as inexpensive as some systems we looked at, but it's the cheapest we found that still offers all the filtration you need to get pure RO water, as well as all the extra features that make the system easy to use (such as a tank, and standard fittings for two typical US sizes).

The system is NSF 58 certified to remove 94% of TDS. It also removes up 1,000 other contaminants, just as any higher-priced RO system will do, including arsenic, phthalates, pharmaceuticals, heavy metals, pesticides, herbicides, fluoride, VOCs, chlorine, chloramine, endocrine disruptors, viruses, protozoa, bacteria, iron, rust, and many more.

It's probably got the best installation instructions of all the RO systems we review here, as well as standard color-coded tubing and connectors. There are also videos and a customer service staff to help if needed.

It has a built-in leak detector which will shut down the system if it detects moisture.

It comes with an extra set of filters, which is a great deal. And the filters are cheap to replace (more on that below).

If you want to add extras, like a remineralization filter, a UV filter (necessary for well water), or a permeate or booster pump to increase water pressure, it's easy to do, as the system is designed for it.

It has a great looking faucet, the nicest (we think) of all the RO systems we review here:

Express RO5D faucet

Overall, it has all the features and the filtering capability of a more expensive system.

Refrigerator Hookup: For about $20, you can get a refrigerator kit to hook the RO5DX to the ice maker and water dispenser. 

What We Don't Like: Probably the biggest thing to not like about the RO5DX is the high ratio of waste water, which is at least 3:1 and maybe higher if your water pressure is not ideal (see specs below). 

The filters are cheap, but they may not last as long as other brands, so you'll have more maintenance to do on this system.

The RO filter housing is a little tricky to open, so it's kind of a pain to change the RO membrane. (Luckily, you only have to do this every 1-2 years.

There's no remineralization filter, but we didn't find this a problem as the water tasted great. If you want to add one, the system is designed for easy add-ons.

Finally, some people complained about cheap parts, poor water quality, and a total daily output way less than 50gpd. We had none of these issues, and thought that overall, if you want to save a few bucks, the RO5DX is a good choice.

The Express Water RO5DX is certified to remove:

  • Heavy Metals: >99.96% (Including Mercury, Lead, Uranium, Chromium VI and more)
  • Chemical Disinfectants: 99.68% (Chlorine and Chloramine)
  • Fluoride: 99.83%
  • Pharmaceuticals: >99.99% (Including Ibuprofen, Caffeine and more)
  • Nitrates / Nitrites: 99.26%
  • Volatile Organic Compounds (VOCs): >99.99% (Sources include paint, varnishes, gasoline, smoke and more)
  • Semi-Volatiles: >99.29% (Including hydrocarbons, ethers, PCBs and more)

Ease of Installation

We think the Express Water system has one of the best installation manuals we've seen. Installation instructions are straightforward and detailed. They include all the information you need.

The system uses color-coded fittings and tubes and will fit both 1/2" and 3/8" inch connections. Here's an installation diagram from the online installation manual to give you an idea:

Express Water RO Installation Diagram from Manual

Some users found the installation instructions hard to follow, which puzzles us. 

Here's the Installation Manual. (Remember that this also has a refrigerator hookup kit that goes for about $20.)

Here's an installation video at the Express website.

Note that the fittings are a little cheap, so you have to be careful not to over tighten, etc.

Express Water also has great customer service and lifetime support, so you should be able to get help if you run into any problems. 

Filters/Filter Changes

Annual Filter Cost: About $125 for 3 year supply; extra set of filters also comes with purchase (so 2-year supply with purchase of RO system).

The Express Water RO5DX system has 5 filters, and the most economical filter prices we've seen in any RO system. This replacement table (from the user manual) is quite handy as it has the filter model numbers:

Unfortunately, Express Water filters tend to have a shorter life than other RO systems. But they're cheap, so depending on your water, you may get up to a year of use out of them (and up to two years for the RO membrane).

Use a TDS meter to check when it's time to change filters, or change if the taste or quality of your water is off. You may be able to get up to a year on the Stage 1-3 filters, depending on your water. 

Most filter changes aren't hard on this system, but they are a little messy. Be sure to have a bucket ready to catch the water when you open it for filter changes. The RO membrane can be hard to get out.

read reviews of express water RO5DX on amazon


Water Pressure Required: 40-80psi @ 40-100F. If your water pressure is below 40 PSI you will need a booster pump for your system. If your water pressure is above 80 PSI you will need a pressure regulator for your system. 

Total Capacity: Up to 50 gallons per day 

Storage Tank Capacity: 4 gallons (holds 3.2 gallons)

Faucet Flow Rate: 0.8 minutes/gallon

Max TDS: 1000ppm

Waste Water: 3 gal per 1 gal of filtered water; higher if water pressure is lower than 40psi and no permeate pump is used.

System Dimensions: ‎16.2 x 18.8 x 18.1 inches (WxDxH)

Weight: 12 pounds

Pros and Cons

  • 99% of 1000's of contaminants removed
  • 50 gpd capacity
  • Built-in lead detector
  • Can use 3/8" or 1/2" fittings
  • Extra filters included
  • Great looking faucet
  • NSF 42, 58, 401 certified
  • Excellent installation instructions and videos available
  • Customizable w/UV filter, alkaline filter, deionization filter, and more
  • Excellent customer service, including lifetime support
  • 1 year warranty.
  • High waste water ratio, 3:1 (or more)
  • Filters don't last as long as some other brands
  • RO membrane housing tricky to open
  • As is, not great for well water
  • Larger than other systems, takes up more room under your sink
  • Some complaints about water quality and cheap components
  • Installation may be hard if you're not a DYI person
  • At least some parts made in China.


The Express Water RO5DX isn't the least expensive RO system out there, but it's the lowest-priced one that still offers the same filtering and storage as more expensive systems. ISo you will get everything you need, plus a supply of filters with purchase. The filters don't last as long as those on other systems, so you'll be replacing them more often. But they're cheap, so you probably come out about the same in the long run with this system vs. the iSpring or APEC (reviewed above). It's a little bulkier than other systems, but it will provide everything you need to get top quality RO water from your city water supply--and if you want add-ons like a permeate pump, UV filter, or remineralization, they're easy to add. The system even has several NSF certifications.

Overall, a nice system, but with the frequent filter changes required, probably not cheaper in the long run than the APEC ROES-50, and certainly a bigger maintenance headache (though not by a lot). Buy only if saving about 50 bucks is critical to your current budget. Otherwise, the APEC ROES-50 is our choice.

Express Water R05DX Reverse Osmosis System
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Best RO System for Well Water: iSpring RCC1UP-AK

iSpring RCC1UP-AK Reverse Osmosis System

See iSpring RCC1UP-AK on Amazon

About $380

Features and Overview

What We Like:The iSpring RCC1UP-AK is an upgrade to the iSpring RCC7AK reviewed above. While the RCC7AK has a remineralization filter for better tasting water, the RCC1UP has that and then some. It's designed for use with private wells, so it comes with a booster pump and a UV lamp.

The booster pump improves water pressure, often needed on well systems, fills the tank faster, and helps improve water pressure at the faucet. Just as important, it improves efficiency, so the waste water ratio is lower; as low as 1:1.

The UV lamp kills pathogens and bacteria that can contaminate well water. Municipal water is treated for pathogens, but well water isn't, so this is an essential feature for private water systems. You do not want the UV lamp on all the time, and this system has a flow sensor that turns the UV on when needed. 

The transparent first filter is a nice feature that makes is easier to see when it's time to change the filter.

The included leak detector is also a nice little extra that iSpring includes. 

Installation is all color-coded, with quick connectors for easy installation. iSpring also has excellent manuals, plus online videos and live support to help you if necessary.

What We Don't Like: Make no mistake, this RO system is big and heavy. It's going to take up a lot of space under a sink, and maybe not fit at all, especially if you have a garbage disposal or use it for storage space.

It also weighs a whopping 30 pounds--more than twice as much as some of our other recommendations.

And you may not need all these parts: if your water pressure is good--above about 60psi--you don't need a booster pump. And unless you're on well water, you don't need a UV filter, because municipal water is already treated for pathogens.

We prefer systems that don't require electricity, but if you're on well water, you'll need the UV lamp, so there's not a lot you can do about that.

A bigger tank would be nice, but the fast water flow makes up for a lot of that.

Finally, this iSpring system is not NSF certified, although the parts it is made from are (according to iSpring).

Refrigerator Hookup: You can purchase an extra line for your refrigerator for about $12 (same kit as for the RCC7AK).

Ease of Installation

As with other reverse osmosis systems, you can install this one if you're handy and have all the tools (drill, spanner wrench, utility knife, flashlight, towels). The quick-connects and color-coded tubing make it easy to follow the procedure. 

You'll need to drill two holes: one into your sink for the faucet, and one into the drain pipe for the waste water. 

The feed water adapter fits both 1/2" and 3/8" connectors, the most common sizes; if you have a different size, you'll need to buy adapters (or, if you're not sure what that means, have a plumber do it).

If you're not handy or don't have the tools to install the system, a plumber can do it in less than two hours.

Here is iSpring's installation video for the RCC RO systems. It's about 11 minutes long and easy to follow.

Filters/Filter Changes

iSpring RCC1UP-AK Reverse Osmosis Filter Change Kit

Annual Filter Cost: $100 for annual filter change kit, plus the RO membrane every 2-3 years for about $30.

Note that the filter change kit includes the UV lamp.

The manufacturer recommends:

  • 3 pre-filters should be changed every 6 to 12 months
  • RO membrane should be changed after 2 to 3 years
  • Activated carbon (GAC) filter and the alkaline remineralization filter should be changed once a year
  •  UV lamp should be changed after 1 to 3 years.

Filter changes are a little fussy, but fairly easy. You have to be sure to turn off the water and drain the system before attempting any filter changes, as well as disconnect the tubes from the filters you're changing. 

This filter change video from iSpring is less than 8 minutes long and covers all of iSpring's RO systems. It's easy to follow and should be a big help in changing the filters.

read reviews of ispring rcc1up-ak on amazon


Water Pressure Required: 40-80psi @ 40-100F. If your water pressure is below 40 PSI you will need a booster pump for your system. If your water pressure is above 80 PSI you will need a pressure regulator for your system. 

Water Pressure Required: 30-70psi @ 40-100F. (The built-in booster pump will raise water pressure to at least 45psi.)

Total Capacity: Up to 100 gallons per day 

Storage Tank Capacity: 3 gallons (holds 2.5 gallons)

Faucet Flow Rate: 

Max TDS: 750ppm

Waste Water: 1 gal per 1 gal of filtered water (with booster pump and water pressure higher than 60psi)

System Dimensions: ‎14.5 x 8 x 16 inches. Tank is 11 x 15 inches.

Weight: 30 pounds.

Pros and Cons

  • 99% of 1000's of contaminants removed
  • Low waste water ratio (2:1 or even 1:1)
  • Easy filter changes
  • Built in booster pump, UV filter, and remineralization filter
  • 100 gpd capacity
  • Fast fill rate w/booster pump
  • Free lifetime tech support
  • Easy installation, with excellent instructions and videos available
  • 1 year warranty/30 day money back guarantee.
  • Electricity required for UV lamp and booster pump
  • Too big for some under-sink spaces
  • May not need booster pump if your water pressure is good (60psi)
  • Don't need UV lamp unless you have well water
  • Lots of filters to change/higher maintenance than other systems
  • Not NSF certified
  • Installation may be hard if you're not a DYI person
  • Made in China.


The iSpring RCCiUP-AK is a comprehensive reverse osmosis system that's a great choice for well water. The booster pump ensures you'll have adequate water pressure and the UV lamp ensures your water will be free of pathogens. If you have well water--or municipal water with pathogen issues--this is one of the best RO options on the market.

iSpring RCC1UP-AK Reverse Osmosis System
Amazon buy button

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Other Types of RO Systems

Under-sink reverse osmosis--also called "point of use" or POU--is the most common type of installation because clean water is most important for drinking and cooking. However, if you're concerned about the quality of all of your water, you can buy other RO systems. The three most common types are whole house, portable, and outdoor.

Whole House Reverse Osmosis System

Example: Commercial RO System by AXEON

For: Not recommended--use a filter meant for a whole house and install RO for your drinking and cooking water.

While you can buy whole-house RO systems, it's typically not a good idea. You don't need RO filtered water for the toilet or for the shower and tub; RO benefits are primarily for drinking and cooking. A whole-house RO system would require a huge tank (200 gallons or more) to hold the filtered water, and most of it would get flushed down the toilet or shower drain.

They're also very expensive, so you can expect to pay about $4000 for a whole-house system. And the waste water generated from RO means a whole-house system would waste a huge amount of water, even if the waste water ratio is low. 

For these reasons, most whole-house water filters are not reverse osmosis. Rather, they soften water and have charcoal filters that remove chlorine, chloramines, and many other contaminants, but no RO filter. 

You can buy a whole-house filter that includes an under-sink RO filter, and those can be a good deal; here's an example of one. But keep in mind that the RO water is only at the point where you've installed the RO filter, typically the kitchen sink. 

If you want more than one RO system in your home, you're better off buying individual under-sink systems and installing them where you need filtered water.

You could also try a commercial system with a larger tank, but even these are designed to work with drinking water, and most won't have the capacity to keep up with the daily water usage of a typical household.

Portable Reverse Osmosis

Example: Aquatrue

For: Non-permanent setups, people who don't want to install a permanent system.

Portable RO systems are great for apartments, RVs, hotel rooms, dorms, or anywhere you want filtered water but don't want to install a permanent system. They work just as well as installed systems so your water will be just as clean with a portable system as it will be with a permanent system.

They're smaller than a standard under-sink RO system, but can still be a little bulky. Some are freestanding and you pour tap water in yourself, and some hook up to the faucet. Note that the vast majority of the faucet types will only work with a standard kitchen faucet, which aren't all that common these days.

Probably the easiest type to use is the Aquatrue linked to above: you pour water in one side, and it produces clean RO water on the other side in less than half an hour. The only downside is that it requires electricity.

Outdoor Reverse Osmosis

Example: LiquaGen Hydroponics RO System

For: Outdoor watering of plants that produce food and watering animals.

If you have a vegetable garden or fruit trees, you may want to use filtered water so your plants don't absorb any of the nasty contaminants from your unfiltered water supply. 

Outdoor systems typically hook up to a garden hose so no tank is required. They may also have a wider range of operating temperatures than under-sink systems, but still won't work well in conditions below about 40F.

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Honorable Mentions

Most reverse osmosis systems work exactly the same way. We recommend getting at least a 5 stage system with a 0.0001 micron reverse osmosis filter (which is what most of them have). If you do this, you are guaranteed to have clean, safe water.

Also read reviews, especially negative ones. Some systems--especially some of the cheaper ones--have non-standard fittings which will involve a trip to the hardware store to get it to work with your plumbing.

So, we don't really have any other systems that came close to making our review--or rather, many systems will work just as well as the ones we chose. 

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Reverse Osmosis FAQs

Here are some common questions about RO systems.

Do Reverse Osmosis Systems Really Work?

Yes. They are the most effective way to remove contaminants from your water. 

Does a Reverse Osmosis System Remove Fluoride?

Yes, typically more than 99% of it.

Are Reverse Osmosis Systems Expensive?

RO systems are expensive compared to pitcher filters and faucet filters, but considering that an RO system lasts several years and does such a great job, they are more than worth the expense: a tank system will run you around $200, or up to about $400 if you need extras like a booster pump and a UV lamp to kill pathogens. A tankless system will be more expensive, starting at around $350 and going up from there.

Filter changes are an added expense that you should take into account. This is a necessary expense and it will vary from system to system. In general, you'll spend about $100 annually to change the filters. 

Are Reverse Osmosis Systems Hard to Install?

They can be, if you're not good at DIY jobs or don't have the right tools (you need a drill). But all RO systems come with good instructions and most offer live support and YouTube videos to help, too. 

If you're not sure you can install one yourself, you can hire a plumber, who should be able to do it in less than 2 hours.

Do Reverse Osmosis Systems Waste Water?

Unfortunately they do. The way RO works, there's always going to be waste water that goes down the drain. The ratio of waste water to filtered water can range from 1 gallon all the way up to about 5 gallons. (Some countertop systems waste only about a quart of water for every gallon of filtered water.) 

If you're concerned about the waste water (for example, if you live in an arid climate), there are a few things you can do:

  • Be sure you buy a system with a low waste water ratio.
  • Maximize efficiency by using the right water pressure (with a booster pump, permeate pump, or pressure regulator).
  • Capture the waste water and use it for non-drinking purposes (such as watering house plants).

Are Reverse Osmosis Systems Healthy?

Absolutely. Installing an RO system is one the best health decisions you can make for yourself and your family.

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Final Thoughts and Recommendations on Reverse Osmosis

Reverse osmosis is one of the best ways to ensure you always have safe, clean drinking water. All water supplies have some contaminants, and only RO can ensure that you're getting the cleanest water possible.

Our recommendations are all excellent systems that should work for just about anyone.

Thanks for reading!

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About the Author

The Rational Kitchen (TRK) is a collaborative effort, but the founder, editor, and writer of most of our articles is Melanie Johnson, an avid cook, kitchenware expert, and technical communications specialist for more than 20 years. Her love of cooking and the frustrating lack of good information about kitchen products led her to create The Rational Kitchen. TRK's mission is to help people make the best decisions they can when buying kitchen gear. 

When not working on product reviews, Melanie enjoys reading, playing with her dog Ruby, vintage video games, and spending time outdoors and with her family.

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