Best Reverse Osmosis System: 10 Models, Reviewed

We may be paid a commission if you purchase through links on this page. This does not affect our opinion or editorial process. More info.

If you’re concerned about the quality of your drinking water, you’re not alone. In fact, many cities have public water systems that don’t even meet EPA standards. Needless to say, this can be bad news for you and your family.

There are many ways to treat your home’s water, but the Environmental Working Group (EWG) has rated reverse osmosis as the most effective method. It removes heavy metal contaminants like lead, arsenic, fluoride, and radium. It also significantly reduces the quantity of total dissolved solids (TDS).

In addition to eliminating contaminants, reverse osmosis systems also make your water more palatable. They improve the color, taste, and smell of your home’s drinking water.

A reverse osmosis filter system even saves you money, since you won’t have to keep buying plastic water bottles!

Let’s look at the best reverse osmosis filter systems on the market. After that, we’ll dig deeper with a detailed buying guide. Let’s get started!

best reverse osmosis system

Disclosure: We may receive commissions when you click our links and make purchases. This does not impact our reviews and comparisons. All opinions are our own. We pride ourselves on keeping our articles fair and balanced. For more info see our disclosure statement.

Comparison Table

ProductDetailsWhere to Buy

Waterdrop Reverse Osmosis Water Filtration System WD-G3-W

Waterdrop Reverse Osmosis Water Filtration System WD-G3-W**Top Pick**

Type: Under Sink
Filtration Stages: 7
Output (GPD): 400
Tank Size: Tankless
Check Price Now

iSpring RCC7AK Filter System

iSpring RCC7AK Filter System

Type: Under Sink
Filtration Stages: 6
Output (GPD): 75
Tank Size: 3.2 gallons
Check Price Now

BOANN BNRO6SYS Reverse Osmosis 6-Stage Water Filter System

boann bnro6sys

Type: Under Sink
Filtration Stages: 6
Output (GPD): 720
Tank Size: 5 gallons
Check Price Now

Brondell Circle Reverse Osmosis System

Brondell Circle Reverse Osmosis System
Type: Under Sink
Filtration Stages: 4
Output (GPD): 56.9
Tank Size: 1.6-gallon flexible reservoir
Check Price Now

Watts 500016 Five Stage EPA/ETV Verified Reverse Osmosis System

Watts 500016
Type: Under Sink
Filtration Stages: 5
Output (GPD): 25
Tank Size: 3.2 Gallons
Check Price Now

Home Master Artesian Full Contact With Permeate Pump

Home Master Artesian Full Contact With Permeate Pump
Type: Under Sink
Filtration Stages: 7
Output (GPD): 75
Tank Size: 3.2 Gallons
Check Price Now

Apec Water ROES-50 Reverse Osmosis Filtration System

Apec Water ROES-50 Reverse Osmosis Filtration System

Type: Under Sink
Filtration Stages: 5
Output (GPD): 50
Tank Size: 4 Gallons
Check Price Now

3M Reverse Osmosis System, 1/4" Pipe Size

3M Reverse Osmosis

Type: Under Sink
Filtration Stages: 3
Output (GPD): 13
Tank Size: 3 Gallons
Check Price Now

DuPont Three Stage Reverse Osmosis Filter

DuPont Three Stage Reverse Osmosis

Type: Under Sink
Filtration Stages: 3
Output (GPD): 35
Tank Size: 2.8 Gallons
Check Price Now

iSpring WGB32B 3-Stage Whole House Water Filtration System

iSpring WGB32B 3-Stage Whole House Water Filtration System

Type: Whole House
Filtration Stages: 3
Output (GPD): 21,600
Tank Size: Tankless
Check Price Now

The Best Reverse Osmosis System – Our Top Pick

Best Choice

The Best Reverse Osmosis System

Waterdrop WD-G3-W Reverse Osmosis Filter

The Waterdrop Reverse Osmosis Water Filtration System features a powerful, 7-stage filter that leaves your water as clean as a mountain spring. It also includes an attractive, easy-to-use smart faucet.

Attractive design, a high rate of flow, a powerful filter: the Waterdrop Reverse Osmosis Water Filtration System WD-G3-W has it all.

To begin with, the 7-stage filter removes just about every contaminant imaginable. Each one of the three cartridges can be adjusted individually, so you can control the rate of flow as the water moves along. This makes the WD-G3-W versatile enough to work in just about any home, regardless of water quality.

The tankless design makes installation quick and convenient, with no need to make room for a tank. This doesn’t affect the performance, either; at 400 gallons per day (GPD), the WD-G3-W allows for more than enough flow.

To tie everything together, the smart faucet sports an LED ring that changes color to indicate your water quality. The faucet itself also features a brushed chrome finish that will match most kitchen sinks.

Reverse Osmosis Filter System Reviews

Waterdrop WD-G3-W Reverse Osmosis Water Filtration System

waterdrop Reverse Osmosis Water Filtration System WD-G3-W

Key Features

  • Includes intelligent “smart faucet” that monitors water quality
  • Powerful, 7-stage filter
  • Attractive design
  • Easy installation

For lack of a better term, the Waterdrop Reverse Osmosis Water Filtration System WD-G3-W is the best RO system that you can get in the market right now. It gives you everything from great cosmetics to a large quantity of flow.

The WD-G3-W’s most obvious feature is the 7-stage filter. In addition to the primary membrane, it sports pre and post-filters constructed from carbon-derived coconut. This leaves your drinking water with a crisp, clean flavor.

In terms of capacity, the WD-G3-W can handle just about anything. With 400 GPD of output, it can meet almost any demand short of an automatic dishwasher. On the flipside, the tankless design ensures that no bacteria will grow when the filter is not in use.

Not only that, but this RO’s tankless design also means you don’t have to make extra space in your cabinet.

Finally, there’s a brushed chrome smart faucet that completes the package. In addition to looking sharp on the back of your sink, this system also boasts an LED light ring that changes color based on the water quality.

When it’s blue, you’re good to go. When it’s yellow, watch out. When it’s red, it’s time to change your filter.

To be fair, the WD-G3-W system comes at a premium price. But if you want the best reverse osmosis system on the market, it’s with the extra money.

You can read our full review of Waterdrop G3 Review here.

iSpring RCC7AK Filter System

iSpring RCC7AK 6-Stage filter

Key Features

  • Built-in alkaline remineralization filter
  • Quality nickel hardware
  • Easy installation
  • 6 Stage filtration system

Reverse osmosis filters are great for removing heavy metals. Unfortunately, they can also remove healthy minerals, including calcium and iron.

For most people, this is a non-issue. Water contains only minimal amounts of most minerals, and those minerals are much more easily found in food. That said, many people find that mineral-free water tastes “flat”.

If you want the benefits of a reverse osmosis filter system without the downsides, the iSpring RCC7AK Filter System is an excellent choice. The last stage of the 6-stage filter essential minerals, restoring a more “natural” flavor. It also makes your water slightly alkaline, ensuring that the pH reaches a minimum of 7.0.

For all of that, the rest of the filter is also very effective. This system removes over 99 percent of arsenic, fluorine, asbestos, and fluoride, along with 98 percent of lead.

The RO unit itself is well-designed, with all six filter canisters exposed. Depending on the rest of your plumbing, they should be easy to replace without a lot of contortions.

All of this comes protected by a 1-year manufacturer’s warranty, along with a 30-day no-questions-asked return window.

Installation is relatively simple. Once the 3.2-gallon tank is in position, you can use the included 3/8” and ½” adapters to tie into just about any home plumbing system.

BOANN BNRO6SYS Reverse Osmosis 6-Stage Water Filter System

boann bnro6sys

Key Features

  • Large tank capacity
  • Includes PE tubing hub for neat installation
  • Stage 6 adds alkaline and minerals
  • Automatic leak detection system

The BOANN BNRO6SYS Reverse Osmosis 6-Stage Water Filter System is a standard under sink filter with a filter assembly and tank.

What’s not standard is the capacity of that tank. At a full five gallons, it can hold considerably more water than a standard 3.2-gallon tank. Not only that, but the BNRO6SYS can filter an impressive 720 gallons of water per day.

The BNRO6SYS system has the highest capacity of any under sink filter on our list, but it doesn’t shirk on filtration, either. Its 6-stage filter removes the vast majority of heavy metals. It even has a final stage that boosts the pH and restores some minerals to the water.

Installation is a bit of a mixed bag. On the one hand, the large tank takes up more space than most filter systems. On the other hand, the DVD walks you through the process, and a PE tubing hub helps keep everything neat and organized.

The filter sports an automatic leak detection system. If the system detects a leak, it will automatically shut off the flow of water, protecting your home and belongings. A pressure regulator also ensures that water flowing into the filter does not cause damage in the first place.

A small brass faucet is included with the reverse osmosis water filter kit. The color is an odd choice, but aftermarket faucets are not too expensive if the finish turns you off.

Brondell Circle Reverse Osmosis System

Brondell Circle Reverse Osmosis System

Key Features

  • Compact design
  • Innovative flexible bladder tank
  • Water-saving pump system
  • Designer faucet

The first thing you’ll notice about the Brondell Circle Reverse Osmosis System is its slick design. At first glance, the black case looks like a mini computer, or an odd speaker system. But the unusual case just scratches the surface of the Brondell Circle’s outside-the-box design.

The main feature of this RO model is its internal flexible reservoir. Instead of a tank, this inflatable bladder can expand to as large as 1.6 gallons. When the faucet is opened, it will deflate, providing plenty of pressure.

On the one hand, this system’s design makes the Circle very compact. Since the “tank” and filters are all contained in one case. On the other hand, the 1.6-gallon volume is relatively small, and can get frustrating during heavy use.

The Circle benefits from an upgraded pump system that eliminates back pressure. You won’t see this under the hood improvement, but it reduces water wastage by as much as 90 percent.

This reverse osmosis water filter model uses a four-stage water filter to remove the vast majority of heavy metals, as well as most chlorine in your water. In addition to preventing waste, the smart pump system also feeds the filters, ensuring that each filter gets the water it needs, when it needs it.

This reverse osmosis water filter kit includes a chrome faucet. Not only is this faucet attractive, it’s also useful; it sports an LED water quality indicator, similar to the one found on the Waterdrop faucet.

Watts 500016 Five Stage EPA/ETV Verified Reverse Osmosis System

Watts 500016 Five Stage EPA/ETV Verified Reverse Osmosis System

Key Specifications

  • Low daily output
  • Compact design
  • Attractive chrome hardware
  • 5 stage water treatment

If you live alone, or it’s just you and a partner, an ordinary reverse osmosis system can be a bit too much. You have too much capacity, and the membrane suffers from underuse. In that case, a lower-capacity reverse osmosis water filter system is the best option.

The Watts 500016 Five Stage EPA/ETV Verified Reverse Osmosis System is a great solution. With a low, 25 GPD output, you don’t have to worry about under-utilizing your water filter. Despite the low capacity, the filter includes a standard 3.2-gallon pump, so short periods of heavy use aren’t a problem.

The filtration system itself is a five-stage unit, with 

If you live alone, or it’s just you and a partner, an ordinary reverse osmosis system can be a bit too much. You have too much capacity, and the membrane suffers from underuse. In that case, a lower-capacity reverse osmosis water filter system is the best option.

The Watts 500016 Five Stage EPA/ETV Verified Reverse Osmosis System is a great solution. With a low, 25 GPD output, you don’t have to worry about under-utilizing your water filter. Despite the low capacity, the filter includes a standard 3.2-gallon pump, so short periods of heavy use aren’t a problem.

The filtration system itself is a five-stage unit, with dual carbon pre-filters and an additional post-filter. It performs a bit better than a simple three-stage filter, but without the frills of a six or seven-stage filter.

Along with the filter, this system also includes an attractive chrome faucet. This faucet sports a small visibility window that’s supposed to let you see how clean your water is. We couldn’t tell the difference, but the window is a neat looking touch nonetheless.

 and an additional post-filter. It performs a bit better than a simple three-stage filter, but without the frills of a six or seven-stage filter.

Along with the filter, this system also includes an attractive chrome faucet. This faucet sports a small visibility window that’s supposed to let you see how clean your water is. We couldn’t tell the difference, but the window is a neat looking touch nonetheless.

Home Master Artesian Full Contact With Permeate Pump

Home Master TMAFC-ERP

Key Specifications

  • Easy-to-use push-in filters
  • Modular design
  • Built-in permeate pump
  • Added minerals for great taste

The Home Master Artesian Full Contact With Permeate Pump is our best choice if you want to minimize waste water.

There are two features that make it best for this purpose.

First, this system’s filter cartridges have a push-in connection instead of a screw-in. This minimizes water wastage during the changing process, as well as reduces the risk of everyday leakage. Not to mention, the push-in connection is just plain easier to use.

Second, the permeate pump reuses waste water. The brine that is expelled from the filters is used to add pressure to pull more water into the filter. No electricity is required, and your filter is more efficient than most.

The Home Master RO unit includes a seven-stage filtration system that removes virtually all contaminants from your tap water. This system also features an alkaline and mineral filter to restore any lost flavor.

All of this comes protected by Home Master’s five-year manufacturer’s warranty. This is one of the most robust warranties on the market, and it’s a great added value.

Apec Water ROES-50 Reverse Osmosis Filtration System (4-gallon tank)

Apec Water ROES-50 Reverse Osmosis Filtration System

Key Features

  • Large tank
  • Attractive chrome hardware
  • Affordably priced
  • Quick connect fittings

Sometimes, you don’t want a filter system with a whole bunch of extras. Sometimes, you need one that just gets the job done without any unnecessary expense. If that’s what you need, your best choice is the Apec Water ROES-50 Reverse Osmosis Filtration System.

Considering the low price, the filter is actually quite powerful. It consists of a five-stage water filtration that removes not only heavy metals, but also 99 percent of chlorine.

The tank is actually a bit larger than average for an under sink filter, with a capacity of four gallons. This is a 25 percent increase over what you get from your typical 3.2-gallon tank, and allows for more sustained use.

On the downside, this RO’s filter is only rated for 0.035 gallons per minute. Once the tank is empty, it takes nearly two hours to refill.

The faucet that’s included with the kit isn’t anything fancy, but it is lead-free. It will get your water from the tank to your glass, which is all you really need.

The Apec Water filter is covered by a two-year manufacturer’s warranty. At this price point, that’s excellent coverage.

3M Reverse Osmosis System, 1/4″ Pipe Size

3M Reverse Osmosis

Key Features

  • Great choice for RVs
  • Very low output
  • Compact design
  • Easy to install

The 3M Reverse Osmosis System, ¼” Pipe Size is not ideal for most homes. It’s very small, and the 13 GPD output won’t be enough for most people.

That said, it’s not really designed for home use; it’s best for RVs, and it excels in that application.

To begin with, the low output will be perfect for most campers. You’re just washing your hands and maybe a few dishes, and you’re probably not inside much. This means the reverse osmosis water filter system’s 13 gallons will be more than enough.

This 3M filter also comes with a small 3-gallon tank, complete with a ¼” installation kit. This will be incompatible with most homes, but should tie right into most RV sinks with no adapters required.

DuPont WFRO60X-1 Three Stage Reverse Osmosis Filter

Dupont WFRO60X-1

Key Features

  • Very compact
  • Easy to install
  • Simple, no-nonsense maintenance and operation
  • Easy cartridge replacement

There’s really not much to the DuPont Three Stage Reverse Osmosis Filter. It’s a simple, 3-stage filter with no extra bells and whistles. On the other hand, it does have an exceptionally small profile, which makes it ideal for very small kitchens.

This RO water filter takes just a few minutes to install, and the small, 2.8-gallon tank is easy to tuck away in most cabinets. It’s nothing fancy, but it’s a respectable filtration that will get the job done.

iSpring WGB32B 3-Stage Whole House Water Filtration System

iSpring WGB32B 3-Stage Whole House Water Filtration System

Key Features

  • Treats the whole house
  • High volume of water flow
  • Tankless design
  • DIY installation and maintenance

Best For Whole House Use

The iSpring WGB32B 3-Stage Whole House Water Filtration System is the best choice if you want to remove contaminants not just from your kitchen sink, but from your entire home. And with a truly impressive 21,600 GPD of total output, this system can keep up with even the most demanding home.

We should point out that this isn’t technically a reverse osmosis system. However, it removes everything a reverse osmosis system removes, short of TDS. For most whole-house applications, this should be good enough to do the job.

The main advantage of avoiding a true reverse osmosis system here is the flow rate. With a true osmosis system, the flow rate can’t keep up with showers or washing machines. As a result, a large storage tank needs to be installed in your basement.

faster flow rate allows for a tankless system, eliminating this problem.

The iSprings whole house system is backed by an extended manufacturer’s warranty. Make sure to register it, though, or you won’t be covered.

Reverse Osmosis System Buying Guide

reverse osmosis system on display in shops

We’ve made our recommendations, but some of the terminology might have been confusing. We understand. This is a big decision, and you want to know what you’re buying!

Here’s a quick overview of what you should keep in mind while shopping for a reverse osmosis filter.

What Contaminants Does Reverse Osmosis Water Filter System Remove?

Reverse osmosis systems primarily remove heavy metals, as well as electrolytes such as sodium, calcium, and magnesium. The metals and other contaminants removed include the following:

  • Arsenic
  • Barium
  • Cadmium
  • Chromium
  • Copper
  • Cryptosporidium (cyst)
  • Fluoride
  • Lead
  • Nitrates
  • Nitrites
  • Radium
  • Selenium
  • Total dissolved solids (TDS)

In addition, almost all reverse osmosis filters include a carbon pre-filter. These pre-filters will significantly reduce the amount of chlorine in residential water.

What Is Reverse Osmosis (RO) and How Does It Work?

what is reverse osmosis

In today’s world, we take most technology for granted. For instance, when was the last time you thought about how your cell phone works?

Reverse osmosis filtration is similar. It can look and feel like magic, so it can be tempting to treat it like any other piece of technology and just assume that it is magic.

But a reverse osmosis filter can sometimes break down. If you’re going to do any diagnosis or repairs, you need to understand how it works. Here’s a quick breakdown.

A standard carbon filter uses tiny charcoal pellets to remove contaminants from your water. If you’re lucky, it will also remove a sediment filter to keep larger particles from clogging up the primary filter.

These standard filters can be useful for removing certain contaminants. They’re great at removing sediment, as well as certain chemicals such as chlorine. Unfortunately, they don’t remove VOCs, pesticides, heavy metals, sodium, or fluoride.

Contaminants like these will remain dissolved in your water, ultimately ending up in your drinking water. A reverse osmosis filter will remove all of those contaminants.

When combined with a carbon pre-filter, it will even give you the benefit of both filter types. For this reason, most quality reverse osmosis systems include a carbon pre-filter and sediment filter in their design.

That said, the magic of reverse osmosis happens in the filter’s membranes.

How a Reverse Osmosis Membrane Works

how reverse osmosis works

So, how does osmosis work? Technically, osmosis simply means the movement of fluid through a membrane. This might sound complicated, so let’s break things down with a simple example.

Imagine a simple cotton tee shirt. Now imagine that you try to use this tee shirt as a pouch for transporting water. Most of the water will drain out of the shirt, because it’s so porous.

Now imagine there was sand in that water. The sand will be left inside the shirt, because it couldn’t pass through the weave of the fabric.

In this example, your shirt is the membrane, the water is the fluid, and the sand represents the contaminants you want to remove.

Now imagine you try to use a polyester windbreaker as a pouch for carrying water. Depending on the thickness of the fabric, you may even succeed! Moreover, when the water does drain out, even smaller particles of sand and silt will be trapped in the fabric.

Similarly, different membranes have different properties. They allow water to pass through faster or more slowly, as well as allowing different sized particles to pass through.

In a reverse osmosis system, the principle is the same. The only difference is that the membrane is considerably finer. Instead of being as coarse as fabric, the holes are tiny.

In fact, the holes in a reverse osmosis membrane are so small that they work on the molecular level. Smaller molecules, like water, are able to pass through when subjected to a little bit of pressure. Larger molecules, like heavy metals, are incapable of passing through.

Oftentimes, the membrane is backed by waterproof paper or another stiffer material. This backing is more porous than the membrane, and doesn’t filter out any contaminants. It simply helps to keep the membrane from sagging.

What is a Multi-Stage Osmosis System?

If you’ve been shopping around for a reverse osmosis filter system, you may have seen some that are advertised as “multi-stage”. What does this mean?

The short answer is that “multi-stage” applies to almost every reverse osmosis system. A single-stage system would be a terrible investment, for reasons we’ll get into.

The longer answer is that instead of falling for the “multi-stage” trap, you should instead look at how many stages there are and what they do.

Here’s a more detailed explanation.

Why do Reverse Osmosis Systems Have Multiple Stages?

A reverse osmosis membrane can’t function on its own. In fact, it would be worse than useless.

The problem is chlorine. The concentration of chlorine in most residential water can cause damage to reverse osmosis membranes. This damage causes them to fail sooner than they otherwise would, sometimes within days.

To prevent this type of damage, reverse osmosis systems almost always include an activated carbon pre-filter. This pre-filter absorbs most of the chlorine from the water, mitigating damage to the main filter.

Of course, the pre-filter itself is also susceptible to damage. If large particles get trapped in the carbon, it could block the flow of water altogether. To prevent this, most manufacturers have a sediment pre-filter to keep large particles away from the activated carbon stage.

To recap, we have:

  • A sediment pre-filter
  • An activated carbon pre-filter
  • A reverse osmosis membrane

This is the basis of a standard three-stage reverse osmosis filter.

Other multi-stage systems will build on this design, with various pre- and post-filter options. But no matter what else a reverse osmosis system includes, it’s built around a sediment filter, an activated carbon filter, and a membrane.

What do Extra Water Filter Stages do?

We’ve talked about the basics of a multi-stage filter. Now let’s talk about what you can do with those additional stages.

The most common extra stage is a carbon block post-filter. This fourth stage is almost universal on filter systems with more than three stages.

The carbon block post-filter “polishes” the water by removing trace contaminants that were removed by earlier filter stages. Regardless of how many stages the filter uses, it almost always comes last in the sequence. Carbon block filters need to be changed less often than earlier stages, and typically come in their own housing.

In many 5-stage filters, the carbon block filter consists of two separate stages with blocks of different sizes. This is more efficient for removing even the smallest amounts of chlorine. Many 6-stage filters take this even further by adding an additional, third carbon block stage.

Another element you’ll see from time to time is a remineralizer filter, sometimes called an alkaline filter. These filters aren’t really “filters” at all, since they don’t remove anything from your water. Instead, they reduce acidity and add healthy minerals that were removed by the reverse osmosis membrane.

A small number of water filters include an ultraviolet light for killing microbes. Traditionally, these have only been found in sterile environments, but recent world events have caused some homeowners to start using them.

Do You Need a Reverse Osmosis System?

dirty and clean water in drinking glass

Whether or not you need a reverse osmosis system depends, first and foremost, on the quality of your existing water. Are you getting pristine H2O from your tap? Keep on drinking it!

If not, you might want to look for a solution. In many cases, a reverse osmosis system can be your best option.

Here’s a quick overview of what a reverse osmosis can – and can’t – eliminate from your tap water.

What a Reverse Osmosis System Can do

  • A reverse osmosis system can reduce the amount of lead in your water. Lead is a known toxin, which causes high blood pressure, nerve damage, and even psychological symptoms. The less of it in your family’s drinking water, the healthier everyone will be.
  • A reverse osmosis system can eliminate heavy metals. This reduces your risk of cancer and other related diseases.
  • A reverse osmosis system removes other minerals, such as calcium and magnesium. This reduces residue in humidifiers and other evaporative devices.
  • A reverse osmosis system reduces the amount of sodium in your water, giving your more control over your daily sodium intake.
  • A reverse osmosis system will remove most bacteria and parasites. Anything too large to fit through the holes in the membrane will not get through to your drinking water.

There are many obvious reasons you might want to experience these benefits, but one is a bit more obscure. Simply put, most people find that their water tastes and smells better after reverse osmosis treatment.

Not only that, but a reverse osmosis system can actually save you money and help the environment. The fewer water bottles you’re buying, the less you’re spending every day. And the fewer bottles you’re finishing, the fewer you’re throwing out.

That’s a win-win scenario for you and the planet.

What a Reverse Osmosis System Can’t do

  • A reverse osmosis system can’t remove all pesticides. Depending on their chemical composition, pesticides may or may not be removed entirely.
  • The same goes for herbicides. Whether or not they are fully removed depends on the exact chemical.
  • Other agricultural products like fungicides may also remain in some quantity.
  • Dissolved gasses, such as hydrogen sulfide, may also remain.

When it comes to chlorine, your mileage may vary. The more carbon block stages your filter system has, the more chlorine it will remove. That said, no reverse osmosis system can remove 100 percent of chlorine.

It’s also important to note that while microorganisms cannot pass through a reverse osmosis membrane, they can grow on the “clean” side of the filter. As long as there’s a regular flow of water, this isn’t a major concern. But if the filter goes unused for long periods, it can become contaminated.

Under Sink vs Whole House System

under sink reverse osmosis system

When you choose a reverse osmosis system, it’s important to buy the correct size system. In general, there are three different types of reverse osmosis filters:

  • Under sink filters
  • Whole house filters
  • Countertop filters

Countertop filters are in a class of their own. They simply filter one or two cups for you as needed, and they’re good enough for making the odd cup of tea. We haven’t reviewed any of these, but they’re still worth mentioning.

Under sink filters are the most common type of reverse osmosis system, and they’re what we’ve spent the most time talking about. They mount under your counter, and usually include a clean water storage tank to ensure a consistent flow.

Whole house filters purify the water supply for every room in your home, which makes them the most powerful choice of the bunch. And more powerful is better, right?

Not necessarily. Whole house filters require complex installation, and tend to be expensive. They require a large tank, a float valve, and a large re-pressurizing pump.

More to the point, they don’t offer many advantages. The heavy metals and other contaminants removed by a reverse osmosis system are generally harmless when used in a shower, dishwasher, or laundry machine.

That said, there are some specific issues — such as very high sodium — that can be fixed by a whole house water system.

Just remember that a whole house system will lower the chlorine in all your water. Make sure to periodically run sinks and showers that aren’t regularly used, to ensure that you’re not leaving stagnant water in your pipes. Otherwise, you could end up with mold or bacteria.

With an under sink filter, on the other hand, you only remove chlorine at the dedicated water tap. Meanwhile, the rest of your home’s water retains the chlorine it needs to prevent microbe growth.

Do You Need a Storage Tank?

In addition to where you install your reverse osmosis system, there’s a second major design factor to consider; do you want a tank or not? Let’s take a quick look at the advantages and disadvantages of storage tanks versus tankless reverse osmosis systems.

Storage Tank Systems

When you’re using a water filter, the pressure coming out of the filter will be less than the pressure going into the filter. If you’re just filling a glass of water, that’s not an issue. But if you need more pressure, it could become a problem.

A storage tank system solves this problem by dispensing purified water into a reservoir. When you open your tap, the water comes out of the reservoir at full pressure, instead of coming directly from the filter at low pressure.

The downside of these systems is that the tanks have a limited capacity. Once they run empty, you lose water pressure. In addition, if the tank is too large for the water inside to be fully cycled, mold and bacteria can grow in the system.

Tankless reverse osmosis systems

Not long ago, a storage tank was the only way to ensure reasonable water pressure coming out of a reverse osmosis filter. But advances in filter technology have allowed manufacturers to create systems that don’t require a storage tank.

These tankless systems use more advanced membrane material to allow for a higher rate of flow. With a tankless reverse osmosis filter, you can wash dishes and perform other higher-pressure tasks. You also save space, since you don’t need to fit a reservoir under your kitchen sink.

The downside of tankless systems is that they come at a price. In most cases, you’ll pay considerably more than you would for an equivalent standard filter and a storage tank.

Waste Water and Efficiency in Reverse Osmosis Filters

man working on water filter

If you’ve been following along so far, you may have wondered how reverse osmosis membranes keep working over time. Don’t all those microscopic holes get plugged up with contaminants?

They would, but filters use a portion of the water to rinse the membrane. This waste water, called brine, is expelled into your sewer or septic tank system.

Reverse osmosis filters vary widely in efficiency. Some waste as little as a tenth of the water, while others waste more than half.

For under sink use, this isn’t really a big deal. At most, you’re only using a few gallons every day, and the filters are only running while the tank is filling. You won’t notice any difference in your water bill.

For whole house use, efficiency is a much bigger consideration. If you’re installing a whole house system, even a very efficient one, expect to see your water bill go up.

Your Water’s pH – Acidic or Alkaline?

The minerals removed by a reverse osmosis system are almost entirely alkaline. As a result, when the water comes out of your tap, it will be more acidic than your ordinary tap water.

Now, this doesn’t mean that it’s corrosive or dangerous. It just means that the acidity is closer to that of pure water.

Unfortunately, some people find that water tastes bland at lower pH levels. If this is a problem, look for filtration systems with remineralizers. The pH will be higher, and the water will have a bit fuller flavor.

What if I Have Low Water Pressure?

As you may remember from earlier, osmosis depends on water pressure to work. If there’s not enough pressure on the membrane, water will not be forced through, and no filtration will occur.

For most reverse osmosis filters, the ideal water pressure is 60 PSI, which is standard in most US municipal water systems. Below 40 PSI, most filters will cease to function altogether. If your water pressure is that low, you’ll need a pre-filter pump to increase it to a useful level.

In addition, various mechanical parts can also fail. Sometimes, the solution can be as simple as replacing the water filter. Other times, it can require more complex repairs. In any case, fixing filtration problems should be a priority.

Here’s a quick summary of the most common problems that can occur with a reverse osmosis filter system.

The Reverse Osmosis Filters May be Clogged

How often you should change your filters depends on a wide variety of factors. Suffice it to say that they will eventually get clogged. If you haven’t changed them as recommended, your filter’s flow rate will slow to a trickle, and eventually dry up altogether.

If you can’t remember the last time you changed your filters, check them before you go any further.

A Water Line May be Kinked

Sometimes, the most frustrating problems have simple, obvious solutions. Check your water lines, and see if they’re all fully open and properly oriented. While you’re under the sink, check the supply valve and make sure it’s open as well.

Low Storage Tank Air Pressure

Okay, now it’s time to bust out some tools. The good news is that you should only need some pliers, an air pump, and a tire air pressure gauge.

First, shut off your cold water valve, and drain any water in the tank. Next, use the pressure gauge to check the air pressure. It should read between 7 and 8 PSI.

If the pressure is too high or too low, bleed some off our add some air accordingly. Be careful when adding air, though; if you add too much, the tank’s inner bladder can rupture.

The Tank Bladder May be Ruptured

The inner air bladder provides some added pressure to push your water out of the tap. If no other solution presents itself, the bladder may have ruptured. In that case, your only option is to replace the entire storage tank.

Municipal Water Pressure May be Low

Before you throw your old storage tank in the trash, it’s a good idea to check a nearby sink or upstairs bathtub. If those are also suffering from low pressure, your problem isn’t with the reverse osmosis filter, it’s with your municipal water.

Call your local water utility or check their website to see if there is maintenance or another factor affecting your water pressure.

Reverse Osmosis Filter System Installation

plumber installing reverse osmosis system

Reverse osmosis systems themselves are relatively easy to install. We’ll focus on under sink filters for now. If you need to install a whole house system, it’s best to call a plumber.

Can You Do This Yourself?

Installing a reverse osmosis water filter system is relatively simple if you have some experience with basic home plumbing. With a few hours of elbow grease, almost anybody can install an under sink unit.

  • The first step is to mount the history itself on the back or side wall of the cabinet under the sink. Read the instructions first, and ensure that your filters are mounted at the correct height.
  • Next, shut off both the hot and cold water shutoffs, and remove the cold water supply line from the valve.
  • Your filter should include a supply line tee. Install this on the valve, connect the supply line to one side of the tee, and connect the filter inflow line to the other. Trim the inflow line if necessary to ensure a straight run and prevent kinks.
  • Attach the faucet to the sink. On some kitchen sinks, the faucet will fit in the fourth hole in a four-hole setup. In other cases, you’ll have to drill a hole yourself.
  • Set the storage tank in the cabinet, and connect the lines to the faucet and filter. Follow all the manufacturer’s sterilization instructions before you do this.
  • When everything is connected, turn on your water and allow the tank to fill. Once it’s full, you’re ready to go!

How Much Does it Cost to Install a Reverse Osmosis System?

Reverse osmosis system installation costs vary widely based on a variety of circumstances. First and foremost, they depend on what type of filter system you’re installing.

There are also other factors that can affect cost. For example, what is the going labor rate in your area, and how skilled is your plumber? That said, here’s a rough overview of estimated costs.

Filter typeMinimum install costMaximum install cost
Under sink$150$500
Whole house$500$1,500

Reverse Osmosis System Maintenance

Under ordinary circumstances, reverse osmosis systems require minimal maintenance. Most of the construction is simple piping and housing, which will last for decades.

That said, the filters will need to be replaced regularly. Exactly how often will depend on many factors, including the brand of filter.

Regardless of manufacturer, keep a close eye on your carbon pre-filter. As long as that filter is intact, your reverse osmosis membrane will not be receiving damage from chlorine. Conversely, an exhausted carbon filter will quickly lead to a failed membrane.

In general, expect to change your pre-filter about three times as often as you change your membrane. Post filters, if any, will also need to be changed when you change your pre filter.

In all, you’re looking at a very modest price per day. Even counting all three filters, the cost of operation works out to under $0.30 per day.

The Wrap Up

As you can see, each of these reverse osmosis filter systems has something to bring to the table. That said, there were a few that stand out from the bunch.

First, let’s once again take a look at our overall winner, the Waterdrop Reverse Osmosis Water Filtration System WD-G3-W. This is an exceptionally powerful filter, with seven stages and a large, 400 GPD capacity. It also includes a smart faucet, not just any old hardware.

The BOANN BNRO6SYS Reverse Osmosis 6-Stage Water Filter System is a solid choice if you need the maximum capacity. It doesn’t have the same snazzy hardware as the WD-G3-W, but it will filter a whopping 720 GPD.

If money is tight, the Apec Water ROES-50 Reverse Osmosis Filtration System isn’t a bad way to go. It doesn’t have any extra features, but it’s a very effective filter for the price.


Does a Reverse Osmosis System Work Better if it Costs More?

It depends on what you’re looking for. The short answer is that if you’re paying $1,300 for an under sink reverse osmosis system. But depending on what you’re looking for, you may want a more or less expensive system.

How Does Pricing Get Decided?

As with most consumer products, there are two main factors that affect a reverse osmosis system’s price.

The first is the quality of the material. In other words, is the filter going to burst under pressure? Is the sink valve going to fail after a few uses?

In this regard, you get what you pay for. If your filter is the very cheapest on the market, you’ve got to question the quality of manufacturing. On the other hand, if it’s absurdly expensive, you’re probably overpaying for material.

The second factor is what we like to call “bells and whistles”. In other words, what extra bonus features does your filter offer?

If you’re buying a bargain basement filter, don’t expect to see any extras. On the other hand, if you want your filter to come with a companion smartphone app, expect to see a hefty price tag.

A good example of how this pricing system works is our top filter choice, the Waterdrop.

You can find a 7-stage filter that cleans your water just as well for half the price. Similarly, you can find a chrome faucet for half the price. But can you find both of those features, as well as an LED ring with filter alerts?

As we said, you get what you pay for.

How Much Should I Pay for RO Filtration?

How much you should pay depends entirely on what you need.

The first thing you should ask yourself is which features you’re willing to pay extra for. Now, shop around and see what you can expect to pay for those features. Check your budget, and winnow your choices accordingly.

The one thing you should absolutely not do is compromise on build quality. You might save a few dollars today, but you could end up with a flooded kitchen in the future. Strike the very cheapest filters off your list, and you’ll be less likely to end up with a dud.

How Long Reverse Osmosis Water Filter System Lasts For?

Most parts of a reverse osmosis system will last indefinitely. Unless something goes seriously wrong, PVC pipes and housing will last as long as metal plumbing.

When it comes to the membrane, you can expect to replace it anywhere from every few months to every five years. It depends on how contaminated your water is, how much you’re using, how fast you’re using it, and how durable the membrane is.

As you can imagine, this means that your filter’s durability can vary widely. Check your owner’s manual for a better estimate.

Does A Reverse Osmosis System Require Electricity?

No, reverse osmosis filters do not require electricity. They will continue to operate, even if your home’s power has been knocked out. As long as your residential water supply has a pressure of at least 40 PSI, you won’t have any problems.

Can I Hook My Reverse Osmosis System to My Refrigerator or Freezer?

In most cases, yes. For an under sink unit, you simply need to run a ¼” tube to the back of your appliance. Depending on the distance involved, this may require an extension tube.

One issue you may run into is water pressure. Most reverse osmosis systems decrease pressure to about ⅔ of the incoming line pressure, so check the pressure your fridge requires. Provided your incoming line has good pressure, it shouldn’t be a problem.

Will My Water Softener Damage My RO Filter?

No. As a matter of fact, soft water is a healthy thing for your reverse osmosis membrane.

Water softeners remove calcium and magnesium, which are two minerals that put a lot of wear on a membrane. On the other hand, the sodium added by the water softener is very easy to remove.

In fact, if your water is too hard, it can cause your membrane to fail prematurely. By all means, keep using your water softener!

I Have Hard Water – Can I Still Use a Reverse Osmosis Water Filter?

Most reverse osmosis membranes require water with less than 0.3 parts per million of iron and a hardness of less than 10 grains per gallon. More than this, and you risk damaging your system.

The exact water hardness requirements of your reverse osmosis filter will depend on your filter material and manufacturer. Our estimates are just general guidelines; when in doubt, defer to your owner’s manual.

I’ve Heard That Reverse Osmosis Doesn’t Remove Chlorine – Is This True?

This claim is often made by advertisers, because it’s technically true. Unfortunately, this fact is taken so out of context that it may as well be an outright lie.

In and of themselves, reverse osmosis membranes don’t remove chlorine. However, chlorine is damaging to the membrane itself.

Because of this, reverse osmosis systems include a carbon pre-filter which does remove chlorine. If they didn’t, the membranes would fail after filtering just a few gallons!

I’ve Heard That Reverse Osmosis Removes Healthy Minerals – Is This True?

Reverse osmosis filters do indeed remove the majority of mineral content from your water. But much like the claim about chlorine, this leaves a lot to be said.

The problem here is that most minerals that are dissolved in water are inorganic. This makes them difficult for your body to absorb. Conversely, the minerals in food are organic, and can be easily assimilated by your body.

In other words, even if your water has zero mineral content, there are virtually no health effects.

On the other hand, many people dislike the taste of mineral-free water. They find it flat and unpleasant, which is just a matter of taste.

Remember, the main health issue with water is not minerals; it’s chemicals. If your water has high levels of arsenic, that’s a major problem you need to fix right now. If you’re getting a few less micrograms of calcium per day, it’s a less pressing concern.

Can I Replace Those Minerals?

Many people remain concerned about the removal of minerals from their water. If this is an issue for you, whether for flavor or for your health, there are solutions.

Many reverse osmosis systems incorporate an alkaline layer or remineralization layer. These layers restore your water’s natural mineral balance, as well as raise the pH to make it more palatable.

Alternatively, you can use mineral drops or Himalayan sea salt from your local health food store.

Do RO Filters Remove Bacteria?

Yes and no. Reverse osmosis will remove most types of bacteria most of the time.

The membrane itself will capture the vast majority of bacteria, along with many viruses. However, bacteria can grow in a storage tank if it remains stagnant, or in a filter that remains unused.

Not only that, but some bacteria, such as E. Coli, will persist in enough concentration to do damage to your body.

If harmful bacteria are a major concern, you should invest in a UV sanitizer. There are many sanitizers available, and many offer simple in-line installation.

What Does Water From a Reverse Osmosis Filter Taste Like?

Water from a reverse osmosis filter is virtually odorless and flavorless. The reason for this is that the “taste” of water is actually the taste of minerals that are dissolved in it. Water, in and of itself, has no flavor.

Some people find that reverse osmosis filtered water tastes flat. But if your current water tastes or smells unpleasant, you’ll probably experience a marked improvement.

Can I Cook With RO Filtered Water?

Not only can you use reverse osmosis filtered water for cooking, but it’s actually encouraged. There are two reasons for this.

First, unfiltered water can leave residue behind when it’s boiled. This can lead to scaling on pots and pans, as minerals build up on the surface over time.

Second, unfiltered water is an excellent choice for boiled foods like pasta, rice, and beans. It’s also good for coffee and tea, so there’s nothing distracting you from the flavor of your brew.

Is Reverse Osmosis Water Safe For Pets?

Yes, reverse osmosis water is safe for pets. Cats and dogs can drink it without experiencing any negative health effects. It’s actually ideal for aquariums, since it provides a clean baseline to make adjustments from.

What About House Plants?

Reverse osmosis filtered water is generally not the best choice for house plants. Plants have evolved to drink groundwater, including all the dissolved minerals. One exception to this is acid-loving plants, assuming your reverse osmosis system doesn’t use an alkaline post-filter.

Is Reverse Osmosis Environmentally Friendly?

As we already mentioned, reverse osmosis filters do produce some minimal amount of waste water. This is necessary to flush minerals and heavy metals away from the filter and keep it clean.

That said, there are environmental benefits that can significantly offset this small amount of wastage.

The most significant benefit is eliminating bottled water from your home. Every year, Americans discard over 35 billion plastic water bottles. If everyone switched to reverse osmosis, most of that waste would disappear.

Are RO Filters Noisy?

A properly functioning reverse osmosis system should be very quiet. While the unit is running, you should hear a gentle whoosh, along with a potential gurgle. These sounds are normal, and they’re nothing to worry about.

If you have a storage tank, the filter should be completely silent whenever the tank is full. A tankless system may continue to gurgle occasionally even when there’s no water running. This is waste water being expelled from cleaning the filter.

Other sounds, such as hissing, may indicate an air or water pressure problem. Call a plumber, or attempt the repair yourself if you’re up to it.

Is Reverse Osmosis Similar to Distillation?

Reverse osmosis is both similar to and different from distillation. It’s similar in that it removes almost all dissolved solids, including salts and heavy metals, but the process is very different.

As we’ve already discussed, a reverse osmosis filter removes contaminants with a microscopic filter. It literally catches heavy metal molecules in a net.

Distillers work by boiling water, collecting the steam, and letting the steam drip down into a new container. Heavy metals don’t boil away, and are left in the original container.

Is Bottled Water Cleaner Than Reverse Osmosis Filtered Water?

It depends on where it comes from. Some bottled water is filtered or collected from actual springs, and is of very high quality. Other bottled water is just bottled tap water, and may not even be as clean as your existing tap water.

Do you have any questions relating to this article? Email us at e[email protected] or call us on +1 (310) 961-4908

This content may contain affiliate links. If you purchase through these links we may be compensated. More info.

Photo of author
Aaron is the founder of and Essential Home and Garden. With over 15 years of hands-on experience in home ownership, lawn care, and gardening, Aaron is a seasoned expert in areas like lawn care, DIY, HVAC, and pest control.

Leave a Comment