All reverse osmosis systems, no matter the brand, style, or price, use a membrane to remove 95- 98% of total dissolved solids (TDS) in addition to carbon or sediment RO filters. So why are some RO systems more expensive others, and how do you know which one to choose? This buyer's guide will help you understand the differences and select the best reverse osmosis system for your home. 

What does a reverse osmosis system do?

A reverse osmosis system does much more than a typical water filter. Reverse osmosis combines carbon and sediment filtration with an RO membrane to remove dissolved solids reduction for a full spectrum of contaminant removal. Of the types of membrane filtration (reverse osmosis, ultrafiltration, nanofiltration, and microfiltration), reverse osmosis is the most extensive. Most residential RO systems don't need electricity to operate. Instead, they run on water pressure.

Reverse osmosis systems use water pressure to push water through a semipermeable membrane to remove dissolved solids. If your water contains high levels of total dissolved solids (TDS), then a reverse osmosis system may be the best option for your home. 

The Best Reverse Osmosis Systems

  1. Flexeon BT-2000: Best whole house RO system
  2. Neo-Pure RO-4300: Best under-sink RO system
  3. Flexeon 5-Stage: Best RO system for saltwater aquarium 
  4. Pentair FreshPoint GRO-350B: Best RO system for RV
  5. Neo-Pure RO-4300 DLX: Best RO system for environment

Reverse Osmosis System Reviews

Flexeon BT-2000- Best Whole House Reverse Osmosis System


  • Well-designed
  • Pre-assembled
  • Easy to operate


  • Complicated installation
  • May require extensive pretreatment

Commercial reverse osmosis systems work best for whole house treatment, but they're often confusing to operate. The Flexeon BT 2000 is simple to use and effective. Here are the characteristics that make this RO system worth the investment:

User-friendly design

Operating a whole house RO system may seem daunting, which is why we recommend the BT 2000. It comes pre-assembled and wired for plumbing. It's also pre-mounted on a stand, so you don't have to mount it to a wall. The system is ready to operate as soon as it's plugged to the feed water, drain, and effluent lines. Installation complexity comes with where you choose to install it. Installation is straightforward but may be difficult for someone without plumbing experience.  

Easy operation 

The RO unit expands and contracts for simple filter changes and servicing. The system is lightweight and easy to transport if needed. You can adjust the meters, gauges, and valves with minimal effort. 

Make sure you consult a water specialist before installing a commercial RO system to make sure you have a suitable application and proper pretreatment based on your water supply. 

How often to replace the RO filters

Neo-Pure RO-4300- Best Under-Sink Reverse Osmosis System


  • Easy to install
  • Low profile
  • Eco-friendly
  • Pharmacy-trusted
  • Membrane monitor
  • Extended contact filter


  • Complicated filter changes

The Neo-Pure RO-4300 is designed for easy installation and a perfect fit under your kitchen sink. Here's what makes the Neo-Pure a great under-sink water filter: 

Eco-friendly filter cartridges

You don't need to worry about contributing to plastic pollution when tossing out an old Neo-Pure filter cartridge. Quick-change filters are encapsulated in a plastic housing that gets discarded with the filter, but Neo-Pure RO filters contain no plastic, only carbon.  Keep in mind that changing these eco-friendly filters is not as simple as replacing a quick-change filter. 

Pharmacy-trusted filtration 

Major pharmacies across the United States, including Walmart and Walgreen's, trust this reverse osmosis system to treat water used to reconstitute antibiotics. This pharmacy-trusted system brings the same quality of water to your tap.

How often to replace the RO filters

Flexeon 5-Stage- Best Reverse Osmosis System for Saltwater Aquarium


  • DIY installation
  • Low maintenance cost
  • Built-in booster pump
  • High output


  • Difficult filter replacements
  • Takes up space

If you have an aquarium, you know that quality water provides your fish a safe and comfortable habitat. Reverse osmosis water is best for a salt-water environment because it removes dissolved solids that could make marine life sick. The Flexeon 5-stage RO system is the best choice for your aquarium-- Here's why: 

Total salt removal

Like any other RO system, the Flexeon 5-stage removes 95- 98% of TDS. With the Flexeon, however, you can add a deionization (DI) cartridge to lower TDS to 0 ppm. Once the water has been stripped of all dissolved solids, you can add just the right amount of salt back in so your fish can't tell the difference between their tank and the ocean. 

Made for high-output

After cleaning your aquarium, the tank needs to be refilled quickly, but RO systems produce water slowly. Adding a booster pump helps the system produce water faster but is an additional expense. This Flexeon system comes with a built-in booster pump to increase water flow.

How often to replace the RO filters

Pentair FreshPoint- Best Reverse Osmosis System for RV

Pentair FreshPoint 3-Stage RO 


  • Fits in tight spaces
  • Click-to-lock filter cartridges
  • Special lead-reduction cartridge


  • More expensive filter replacements
  • Not as eco-friendly

If you're looking for an RO system for your RV, then installing the Pentair FreshPoint is a no-brainer. 

Compact design

If you have an RV, then you may be reluctant to install extra components that take up space. We recommend the FreshPoint for RV owners because they're designed for tight spaces. The filter housings open toward you, allowing you to pull the filter forward and replace it in no time. Other under-sink RO systems need additional clearance above or below to remove the housings and change the filters. 

Click-to-lock cartridges

The FreshPoint filters are considered "quick-change" because they can be replaced with a single click. Keep in mind that ease of maintenance comes at a cost to the environment. The FreshPoint filters are encased in plastic that will end up in a landfill. 

How often to replace the RO filters

Neo-Pure RO-4300 DLX- Best Reverse Osmosis System for the Environment 


  • Saves water
  • Alkaline water
  • Pharmacy-trusted


  • Complicated filter changes

Reverse osmosis systems are criticized for wasting water and removing beneficial minerals, but the Neo-Pure RO-4300 DLX eliminates both problems. This system comes with two additional components that classify it as "deluxe": a permeate pump and a remineralizing filter. 


A reverse osmosis system with permeate pump saves 85% more water and enhances performance. The Neo-Pure RO-4300 DLX is one of the few systems suited for a permeate pump, and the pump is included in the package. 


This Neo-Pure system also comes with an Aptera alkaline water filter. The reverse osmosis process removes beneficial minerals like calcium and magnesium from water and lowers the pH. The alkaline water filter corrects the pH to reduce acidity and adds a mineral flavor by dissolving calcium and magnesium into the water. 

How often to replace the RO filters

Do you need a reverse osmosis system?

Reverse osmosis is one of the most thorough filtration systems when removing contaminants, but your water may not need such thorough filtration. You should first conduct a water test and determine what’s in your water before selecting any filtration system. Reverse osmosis systems are most often installed under a sink in homes to filter drinking water with high levels of TDS. 

Reverse osmosis systems are great at getting rid of dissolved inorganics, including arsenic and fluoride. But for contaminants like chlorine and taste and odor issues, you may not need a system quite as extensive. An RO system reduces many contaminants including minerals, but it does not remove certain bacteria or viruses. If you need living organisms removed from your water, then a UV system is the best option. If you want to receive extensive filtration while retaining minerals, then you may prefer an ultrafiltration system.

When you may need an RO system:

  • With high levels of TDS in water
  • With harmful dissolved solids like arsenic or nitrates
  • When you need to reduce sodium in water
  • When you need extensive filtration for a pharmaceutical or aquarium application

Why you may not want an RO system:

  • May require a dedicated faucet installed in your counter
  • May require additional components like a storage tank or booster pump
  • Sends a lot of water to the drain without a permeate pump
  • You live in an apartment or rental and are not permitted to install one

How to select the best reverse osmosis system

Understanding the difference between reverse osmosis systems is not rocket science. Most reverse osmosis systems, commercial and residential, work the same way and produce the same quality water. Finding the best reverse osmosis system for your home depends on your application, budget, and preference. Here are 8 factors that influence which reverse osmosis system you choose.

RO System  Stages Style Output Permeate Pump Remineralization Cost
BT-2000 3 Standard 2000 GPD N N $3,249.99
RO-4300 3 Drop-in 50 GPD N N $199.99
Flexeon 5-Stage 5 Drop-in ? N Y $357.49
GRO-350B 3 Quick-change 50 GPD N N Call to order
RO-4300 DLX 4 Drop-in 50 GPD Y Y $319.99


8 things to consider when buying an RO system

1. Water source

The water that enters your home feeds the reverse osmosis system. City water or municipally treated water is relatively free of chemicals and bacteria but may contain inorganic dissolved solids, which an RO system is designed to reduce. Private well water could contain harmful pathogens and chemicals in addition to dissolved solids.

Reverse osmosis systems can treat both city and well water, as long as the well water has been pretreated for bacteria and particles that could clog the membrane. If you’re on well water contaminated with heavy metals like arsenic, then you may need a UV system to disinfect the water once it leaves the storage tank.

2. Water demand

Consider how much water you and your family are going to use. Every person, according to nutritionists, should drink half their weight in ounces every day. So, if you weigh 160 pounds, then you should be drinking 80 ounces of water per day. You also have to take water used in ice machines, refrigerators, and all your other appliances into account. Each reverse osmosis system provides the amount of water produced each day, measured in GPD (gallons per day).

3. Water pressure

Reverse osmosis uses water pressure to force clean water through the membrane. If your household water pressure is below 40 psi, then you need to increase the pressure for reverse osmosis with an RO booster pump. If you're on well water supply, make sure your tank’s water pressure is set high enough for an RO system to work. A high level of dissolved solids in water also increases the amount of pressure needed for the RO system to produce clean water.
A residential reverse osmosis system is point-of-use, which means you install it right where you need the RO water. Most RO systems install directly under your sink. Whole house reverse osmosis systems are used less often because they require a large storage tank and booster pump for adequate pressure to supply water to every point in your house.

4. RO style

Reverse osmosis systems come three different cartridge styles: quick-change, drop-in, and standard. Your choice of filter style depends on whether you prefer easy maintenance, low maintenance cost, or the least environmental impact.

Quick-change cartridges: simplest to maintain, but also the most expensive and the least environmentally-friendly. 

Quick-change filters are easy to replace. Simply twist the filter and pull it out. Then, take the new filter and turn it in the opposite direction to replace the old one. However, the ease of maintenance comes with a high price tag, and the filter cartridges are made of plastic that gets wasted every time an old filter is discarded.

Drop-in and standard cartridges: More difficult to replace, but also the least expensive and most environmentally friendly.

To replace a drop-in or standard filter, unscrew the housing, throw the filter cartridge away, put a new cartridge in, and put the housing back in its place. Standard filters can be replaced with compatible cartridges, but drop-in systems require exact replacements.

Reverse osmosis systems also come in different stages, usually three, four, or five, based on the number of prefilters and postfilters included. The RO membrane does most of the work removing dissolved solids, but additional prefilters and postfilters can polish, re-mineralize, and provide additional chlorine and sediment removal. Eventually, the membrane wears out, but prefilters give an initial pass through filter media to help extend the life of the membrane.

5. Budget

When budgeting for a reverse osmosis system, you have several factors to consider: How much does the system cost? How much will installation cost, especially if you hire someone? How much does on-going maintenance cost? These factors may affect which RO system you choose or whether or not you use one at all.

How much does a reverse osmosis system cost?

The price of a reverse osmosis system varies depending on whether you need one under your sink or for your whole house and how many additional components you need. Whole house RO systems are much more expensive and complex. Under-sink RO systems usually range from $200 to $400 depending on the style. The cost increases if the system doesn't include a booster pump, permeate pump, storage tank, or pretreatment.

Installing any RO system is an investment that requires on-going maintenance costs, including replacement filters and membranes. The replacement cost and frequency depend on your style of an RO system. Generally, the RO membrane needs replacing every two years, and the filters need replacing every six months to one year. The reverse osmosis system itself lasts twenty years or longer with proper care.

Factors that influence the cost of an RO system:

  • Type of system
  • Pretreatment
  • Installation cost
  • Maintenance cost
  • Additional components
RO System Ease of Installation Ease of Maintenance Annual Replacement Frequency Annual Maintenance $ Maintenance $ w/ Membrane
BT-2000 Complex Complex

Filters: 2

Membrane: Every 3 years

$173.25 $278.40
RO-4300 DIY Moderate

Prefilter: 2

Postfilter: 1

Membrane: Every 2 years

$53.22 $87.74
Flexeon 5-Stage DIY Moderate

Prefilters: 2

Postfilter: 1

Membrane: Every 2 years

$12.00 $65.02
GRO-350B DIY Simple

Prefilter: 2

Postfilters: 1

Membrane: Every 3 years

$62.23 $111.64
RO-4300 DLX DIY Moderate

Prefilter: 2

Postfilters: 1

Membrane: Every 2 years

$53.22 $183.66


6. Ease of Installation

Most under-sink reverse osmosis systems are easy to install. However, installing an under-sink RO system requires a dedicated faucet, which means you may have to drill a hole in your countertop. If you're not comfortable doing this job yourself, then you may need assistance from a plumber or a handy friend or family member.

Reverse osmosis systems must have a dedicated faucet and a drain connection to prevent the dirty drain water from flowing back into the clean drinking water. An RO system cross-connects the drain line and the water line. Plumbing code requires that cross-connections have an air gap faucet that allows drain water to pass through without returning to the clean water.

Learn how to fix an air gap leak.

Consult a water specialist before installing a whole house reverse osmosis system to make sure there's not a simpler, equally-effective solution and to make sure you apply proper pretreatment based on your water conditions.

7. Efficiency 

A reverse osmosis system is not the most efficient filter. After reverse osmosis filters contaminants, it sends them to the drain with a significant amount of water. However, this water is not exactly wasted since it's used to carry contaminants away and make potable water.

Standard water filters collect contaminants on their surface, but the RO membrane stops them and uses water to carry them to the drain. Adding a permeate pump to your RO system makes it 85% more efficient. The permeate pump uses the wastewater as energy to send clean water to the storage tank. The most environmentally-friendly RO systems include a permeate pump or allow you to add one.

Learn how a permeate pump works with a reverse osmosis system.

permeate pump chart

8. Remineralization

Reverse osmosis removes dissolved solids from water and reduces alkalinity or lowers water's pH in the process. The lower pH makes the water slightly acidic. Acid water is corrosive, but adding an acid neutralizing filter, like a calcite filter or alkaline water filter, increases the pH adds mineral flavor. The Aptera filter dissolves calcium and magnesium in water and reduces scale, microorganisms, and sediment through several stages of remineralization.

water pH scale

Whole house vs. under-sink reverse osmosis system

A commercial RO system is installed in a home when whole house reverse osmosis treatment is the best solution to a specific problem. Reverse osmosis systems are most commonly installed under the sink to treat only the drinking water. Most people would benefit from an under-sink RO system, but a whole house RO system is rarely necessary. If your water contains dangerous contaminants that only reverse osmosis can treat, then a water specialist can help you find out what pretreatment and additional components are needed.

A reverse osmosis system vs. a water softener

A reverse osmosis system does remove minerals like calcium and magnesium that cause hard water, but it's not designed to soften water. A water softener is installed at the point of entry to treat the whole house and is much less expensive and much more efficient than whole house reverse osmosis at treating hard water. Water softening exchanges mineral ions with sodium to remove hardness instead of filtering out the minerals like reverse osmosis. Adding an under-sink RO is a great way to remove extra sodium added by the softener.

Is a reverse osmosis system worth it?

If your drinking water contains high levels of TDS or harmful dissolved contaminants like silica, nitrates, or arsenic, then an RO system is certainly worth the investment. No other system, besides a distiller, removes dissolved solids as extensively as an RO system, which makes RO a great option for aquarium owners. 

A reverse osmosis system’s worth is best described by the reasons why you want or need one. Reverse osmosis removes nearly 95% of particles and dissolved contaminants from drinking water. It does this through a natural process using simply the force of household water pressure without any chemical additives. Your beverages, ice, recipes, and drinking water are all enhanced with RO water.

Reverse osmosis systems & filters reviewed by our guests

5 stars for the Neo-Pure RO 4300RX

Excellent System | Great Value

The Neo-Pure RO 4300RX is a fantastic filter system and a great bargain. The specialist spent nearly an hour on the phone helping me to understand the product before purchasing, and their customer service was very helpful in answering my post-installation questions. I'm not a plumber but I was able to install the system myself in a few hours, and we are quite satisfied with the product. -- Fred. T.

5 stars for the Omnipure replacement RO filter

Good Deal

The right filter for the right price. -- Robert H.

Easy To Install

I would buy this product again. -- Judy C.

5 stars for the Neo-Pure replacement RO filter

Economical General-Use Filter

We use this for filtering general use water at the spigot in the brewery and change monthly for best results. -- Gregg L.

Stage 2 of a 3-Stage Filter System

This is the heart of my 3 stage system. It takes away nearly every pollutant that is missed by the local water utility. The minerals which are needed for health are not removed from the water namely calcium. -- Bill A. 


  • My experience with Fresh Water and particular with its Technical Sales Manager John Woodard were excellent, services hard to come by these days. John patiently wrote me at least 5 emails, in his attempt to help me solve problems with my Reverse Osmosis system. He pro-actively stopped my order when he thought that I had ordered the wrong spare part, and made sure I got the right part. Excellent services and I can certainly recommend their business, without hesitation.

    Johan on

  • John Woodard was helpful, knowledgeable and patient. Their reverse osmosis filtering system is excellent. I bought from Freshwater Systems for approximately ten years and their products and systems are top quality.

    Barb on

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