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Tankless Reverse Osmosis Systems

Most Efficient!
Efficiency Series Tankless Reverse Osmosis System
Ideal for those who want to save space and still get delicious, filtered water!
  • High efficiency
  • Alkaline & UV Filters available
  • Quick-Change Filters
starting from $265.95 View All Tankless Systems
Would purchase a million times over!
We LOVE the machine!! It is everything we could wish for. We enjoy the ease of filling up at our home and having instantly clean water. It’s super convenient to have hot water on demand.
Makayla Stanford Verified

Countertop Reverse Osmosis Systems

No Installation
Countertop Reverse Osmosis Systems
Ideal for those who want to save space and still get clean, filtered water!
  • UV-C Treatment
  • Zero Installation
  • One-touch automatic dispensing
starting from $228.95
Countertop Reverse Osmosis System NU Aqua CTRO Ambient In Kitchen
Best apartment upgrade I've made
I rent an apartment and couldn't install anything under the sink — this was the perfect solution. No plumber, no holes, just plug in and done. The water quality is night and day from tap, and the hot and ambient dispense feature means I use it for everything — coffee, cooking, drinking. Genuinely one of the best purchases I've made for my kitchen.
Rachel T Verified

Reverse Osmosis Deionization

No Installation
Reef Series 4 Stage 100 GPD RODI Reverse Osmosis System
Professional grade system designed for aquariums, hydroponics, and homebrewers!
  • Zero TDS
  • Includes Hose and Faucet Adapters
  • Extra Large Resin Filter
starting from $159.95
My tank loves it!
System came packaged nicely with straight forward instructions. After flushing the system the water was coming out at 0ppm. I keep fresh water and salt water tanks and have used this for both. Getting an rodi system has saved me a lot of time going to the local fish store to purchase water. I highly recommend this for anyone who has a fish tank.
Jake Roberts Verified

Compare All Systems

Which Reverse Osmosis System Is Right for You?

All four systems produce the same clean, filtered water. The difference is how they fit your home, your household, and your lifestyle.

Reverse Osmosis System NUAqua Tankless600 Main
Most Efficient Tankless RO Efficiency Series
NU Aqua RO System 5 Stage Side
Best Value Classic RO Platinum Series
Countertop RO System
No Installation Countertop RO Countertop Series
Reverse Osmosis System NU Aqua RODI Main
Specialty RODI System Reef Series
Best For Space-saving, high-output households Budget-conscious buyers, standard kitchens Renters, no-plumbing setups, offices Aquariums, reef tanks, hydroponics
Installation Under-sink Under-sink Zero installation Countertop / freestanding
Storage Tank No tank Pressurized tank No tank No tank
Flow Rate 600–800 GPD 100 GPD Dispensing on demand 100 GPD
Water Efficiency 2:1 pure-to-waste 3:1–5:1 waste ratio Varies by model Standard RO ratio
Under-Sink Space 25–50% of standard RO Full cabinet + tank Countertop only Countertop only
Requires Electricity Yes (booster pump) No Yes No
Filter Changes Tool-free twist-lock Standard housings Varies by model Standard housings
Alkaline & UV Options Yes Yes UV built-in Not applicable
TDS Output 95–99% reduction 95–99% reduction 95–99% reduction 0 TDS (RODI)
Starting Price $284.95 $169.95 $239.95 $169.95
Shop Tankless → Shop Classic RO → Shop Countertop → Shop RODI →

Reverse Osmosis Water Filter Buyers Guide

If you’re looking for exceptionally clean, great-tasting water at the turn of a faucet, a reverse osmosis system is for you. Under-sink systems are tucked away out of sight and come with a separate countertop faucet that dispenses your filtered water.

These systems work well in homes, apartments and offices. Whether you’re on city water or well water and want added UV treatment, we have a system that will work for you.

reverse osmosis system installed under kitchen sink

What is a reverse osmosis water filtration system, and how does it work?

In recent years, reverse osmosis water filters have become a popular option for drinking water at home and at work. Reverse osmosis, commonly called RO, uses water pressure to push water through a semipermeable membrane that reduces dissolved solids, ions, and other impurities. In a classic RO system, the filtered water is stored in a pressurized tank, ready for drinking or cooking. Tankless systems filter water on demand instead.

Why is reverse osmosis the most common household water filtration method?

RO systems are very low maintenance

RO is more affordable than buying bottled water

RO is highly effective and efficient 

RO is environmentally friendly

RO produces some of the best tasting water

How Do Reverse Osmosis Systems Work?

The term may sound complicated, but reverse osmosis filtration is actually quite simple. RO uses your home’s water pressure to push tap water through a semipermeable membrane. Water molecules are small enough to pass through the membrane’s tiny pores, while larger dissolved solids such as salts are rejected and flushed down the drain.

How much does a reverse osmosis water filter cost?

No longer are reverse osmosis filters too expensive to afford for home use. With most systems ranging in cost from $150 - $300, it’s no surprise why so many people have switched to filtering their drinking water at home. While some may argue that even with the price of the system being more affordable the other costs of replacements and waste water still make it expensive. Let’s break it down and take a look at how much it will actually cost.

Cost Breakdown
Reverse Osmosis System
  • One time purchase of the system: $179.95
  • One person consumes on average 180 gallons of water per year.
  • Average cost per gallon of water from the city: $0.0015
  • Now to get the total amount of water including waster (2:1) waste ratio: 360 Gallons
  • The total cost of water for 1 person: $0.0015 x 360 Gallons = $0.54.
  • Your first year of owning an RO system will cost you approximately $180.59.

Now let’s take a look at your second year of owning an RO system.

  • Replacement filters with membrane: $79.96
  • Water: $0.54
  • Total spent second year: $80.50
Cost Breakdown
Bottled Water Usage

Now to put this into perspective lets compare the cost of purchasing bottled water.

  • One person consuming 180 gallons of water breaks down to 1,368 water bottles per year.
  • The average cost of a 24 pack of water bottles: $4.99
  • The cost per bottle: $0.20
  • 1,368 bottles X $0.20 = $273.60
$273.60
SPENT ON BOTTLES
$273.60
per person
Reverse Osmosis Yearly Cost!

The numbers speak for themselves. Even with cost of purchasing the system you will still save money the first year of switching to reverse osmosis.

First Year Savings: $93.01

Second Year Savings: $193.10

Since you save $193.10 per person, you spend $0.54 to save $193.10 for every additional person in your home or business. That’s a savings of $965.50 for a household of 5!

$193.10
yearly savings
$193.10
per person

Frequently Asked Questions

What makes Reverse Osmosis filtration a good option for home?

The process of reverse osmosis has been around for over 100 years, but it’s energy intensive process made it quite expensive and not a viable option for home filtration. However, over the past 10 years recent improvements in design have allowed companies to produce affordable systems that can be utilized for home use.

What makes Reverse Osmosis better than other forms of water filtration?

If you’re currently searching for a water filter for your home or business this will help you understand the why RO is the top choice for millions of American households.

  1. Most effective method for difficult to remove contaminants: RO systems can remove 1000’s of chemicals such as lead, mercury, fluoride, chlorine, sodium, copper, chloride, chromium, arsenic radium, sulfate, and many more. Unlike standard water filters, pitcher filters, and faucet filters, RO systems can remove PFOA’s which have been an increasing issue with recent water reports.
  2. Minimal Maintenance: RO systems require very little upkeep which entails cleaning and replacing filters which is done approximately once a year depending on your water quality. While these systems may seem complex, they’re actually quite simple. They have very few moving parts and all replacement parts are readily available and affordable.
  3. Saves Time and Money: Once you make the switch to filtering your own water at home you can stop buying cases of bottled water, cancel your water delivery service, and stop buying expensive refrigerator filters that are ineffective. After purchasing a system, your annual cost of replacement filters and water (including waste water) is approximately $40.49. Your average annual savings on bottled water is $233.11 and only doubles with each member of your household.
  4. Clean Crisp Taste: If you haven't tried RO water yet I think you would be surprised when I told you that 90% of bottled water is processed using reverse osmosis. RO systems produce some of the most filtered and best tasting water which is why bottled water companies use the same process.

When it comes to water everyone’s situation is different. Some people may have crystal clear water with no smell, or slightly yellow water with a sulfuric smell. Even if the contamination is not visible your water could be unsafe or bad for your health. Reverse osmosis is the best solution to treat odor, taste, appearance, and provide you with the reassurance that the water you’re consuming is safe.

What does reverse osmosis remove from water?

Reverse osmosis systems are one of the most effective in home water filter systems. They are able to reduce and treat a whole host of contaminants, including:

Cryptosporidium, Giardia, Campylobacter, Salmonella, Shigella, E.coli, Enteric, Sulfate, Calcium, Magnesium, Potassium, Zinc, Mercury, Cyanide, Norovirus, Rotavirus, Sodium, Chloride, Copper, Chromium, Lead, Arsenic, Fluoride, Radium, Nitrate, Phosphorus, Nickel, Phosphorus.

What are the parts of a reverse osmosis water filter?

There are many manufacturers of reverse osmosis systems, and in most cases use similar components and function the same way. However, the big difference is the quality of components, performance, and efficiency. Purchasing a cheap, inefficient RO system can end up costing you more in the long run due to the amount of water they waste and the problems that arise. 

Reverse Osmosis System Components:

  1. Feed water adapter: This attachment installs directly to your cold water line that runs to your kitchen faucet so that it can divert water to the reverse osmosis system. It does not affect the function of the faucet or water pressure.
  2. Polypropylene Spun Sediment filter: This is the most common first stage of a reverse osmosis system. This pre-filter removes visible particulate such as dirt, sand, dust, debris, clay, and rust. Removing these larger particles earlier in the filtration process helps extend the life of membrane and carbon filters in the system.
  3. Granular Activated Carbon Filter: The second stage is where organic and synthetic chemicals such as chlorine, and herbicides are removed. Also known as a GAC filter, granular activated carbon is made from organic material such as wood, lignite, and coal. Due to the increased surface are of a GAC filter they’re highly effective at absorbing and removing bad taste and odor from water.
  4. Carbon Block Filter: Just like GAC filters, carbon block filters are made from wood, lignite, coal, and remove, volatile organic compounds, arsenic and sediment. Unlike granular filters, the carbon in this filter is a solid block. This is beneficial because it forces the water to have longer contact with the filter media which improves it’s contaminant removal. The only downside with carbon block filters is the effect they have on flow rate. Since carbon block filters slow down flow rate it’s best for systems to only use one carbon block filter and one granular carbon filter. 
  5. Automatic shutoff Valve: Reverse osmosis water filtration systems are dependent on water pressure to control when water is being filtered and when the system turns off. The automatic shut off valve or ASOV relies on the pressure from the tank to indicate once it’s full. Once the tank is full the ASOV shuts off water to the membrane and drain. Once water is drawn from the storage tank by turning on the faucet and the pressure drops within the tank, the ASOV opens again and allows the system to refill the tank.  
  6. Reverse Osmosis Membrane: The reverse osmosis membrane or RO filter is where the system does all the heavy lifting and removes the majority of dissolved solids and contaminants. This is the 4th stage on most systems directly following the ASOV. Reverse osmosis membranes are highly effective at removing metal ions, aqueous salts, sodium, chloride, copper, chromium, lead, arsenic, fluoride, radium, sulfate, calcium, magnesium, potassium, nitrate, phosphorus, and PFOA’s. 
  7. Flow Restrictor: To prevent excessive waste and maintain pressure on the inlet side of the membrane a flow restrictor is added on the drain line off the membrane housing. This part is crucial for a reverse osmosis systems to function properly. If there was not flow restrictor water would take the path of least resistance and only flow through the drain line.
  8. Storage Tank: Since reverse osmosis systems typically produce 50-100 gallons of filtered water a day they must use a storage tank so that you have filtered water on demand. These tanks have a pressurized bladder inside that boost the water pressure at your faucet. 
  9. Carbon Post Filter: To ensure your water is clean and odorless it passes through the 5th and final stage which is a carbon post filter. This is similar to the second stage GAC filter and is comprised of activated  carbon.
  10. Optional Ultraviolet Treatment: For homes without adequate filtration of their water it's best to have a UV filter on your reverse osmosis system.
  11. Optional Alkaline Filter: Since reverse osmosis does such a good job of removing dissolved solids it's often a concern that it removes beneficial minerals. Studies show that we receive all the necessary minerals directly from our diet and any we take in from the water we drink is an added benefit. Alkaline filters naturally add back those minerals and increase the alkalinity of the water. 
  12. Faucet: Since reverse osmosis systems operate independently of your kitchen faucet they must have a separate faucet installed. This allows you to use filtered water as you please so that you don’t waste filtered water on washing your hands or dishes. 
  13. Drain line: Since reverse osmosis membranes separate the contaminants in your water they require flushing of these contaminants as waste. This drain line allows this process to be automated and runs directly to your drain saddle.
  14. Drain Saddle: The drain saddle is the final step for your waste water. This attaches on the p-trap or drain under your sink and allows the drain line to connect with ease.

Why do I need a reverse osmosis system?

Whether your water comes from the city or a private well, a reverse osmosis system gives you more control over the water you drink and cook with at home.

City water

Municipal treatment facilities work hard to deliver water that meets EPA standards. Many households still notice the taste or smell of the chlorine and chloramines used in treatment, and water can pick up dissolved solids as it travels through local pipes to your home. A reverse osmosis system filters water right at your kitchen sink, reducing dissolved solids and chlorine taste and odor for cleaner, crisper-tasting water.

Well water

Private wells aren’t treated by a municipal facility, so water quality depends on your local environment and how your well is maintained, and regular testing is recommended. If you’re on well water, a 6-stage reverse osmosis system with a UV filter adds a supplemental treatment stage, and a booster pump option helps if your water pressure is below 40 PSI.

What makes one reverse osmosis system better than others?

If you’re interested in a reverse osmosis system and you’re currently doing your research you will find there are many different systems that all look verysimilar. Where they differ is going to be quality of components, design, and manufacture support.

Quality of components

  1. Filter housings: One of the most important parts of a reverse osmosis system is the filter housings. Cheap housings are prone to cracking with age,poor seals which can cause leaking, and loose fitment of filters that can cause low performance of the system.
  2. Fittings: Each tubing installed on reverse osmosis systems will typically connect by quick connect fittings. These fittings work great and are the best option for connections. However, just like with cheap filter housings, cheap fittings on a reverse osmosis system can lead to a nightmare of leaks and performance problems.
  3. Filters: While the filters in most reverse osmosis systems are universal, not all filters are created equal. Poorly made sediment filters can allow dirt and other sediment to pass through which shortens the life of other filters in the system. Granular carbon filters that do not have enough filter media in them can provide poor performance, and cheap carbon block filters are prone to clogging and an increase loss in water pressure.
  4. Faucet: Let’s face it, RO systems are not the most beautiful appliance you want to see in your kitchen which is why they’re hidden under your sink, however, your faucet sits on top of your counter top at all times. Cheap RO faucets not only have cheap plating that can flake off over time and rust, but they are prone to leaking and wasting water.
  5. Automatic shut off valve: Like mentioned earlier, the automatic shut off valve tells the system when to turn on and off. This is one part you want to have that’s made with quality. A cheap ASOV can cost you lot’s of money in wasted water if constructed poorly.

System Design

  1. Flow Rate: Most reverse osmosis systems will provide anywhere from 50 gallons per day up to 100 gallons per day. For most homes with 3 or morepeople it’s best to have a system that can provide 100 gallons per day to keep up with your water demands.
  2. Number of filters: Everyone’s situation is different and needs a system that works for them. Your standard reverse osmosis system will come with 5stages and have optional alkaline and ultraviolet stages for those of you who prefer alkaline water or need sterilization.
  3. Efficiency: Since not all systems are designed the same, their waste ratios will vary. A good reverse osmosis system will typically produce a 2:1 – 3:1waste to pure water ratio. Systems made with cheap components can have a waste ratio up to 10:1 waste ratio.
  4. Booster Pumps: Most homes with municipal city water have sufficient water pressure but for those who are on well or have low water pressure willrequire a system that features a booster pump. Reverse osmosis systems need a minimum of 40PSI to run efficiently. Even if your water pressure is above40PSI it doesn’t hurt to have the added booster pump. This pump will make sure your system maintains pressure around 80PSI.

Manufacture Support

When it comes to purchasing a reverse osmosis system is important to make sure the company you decide on is not just a reseller but are in fact amanufacture. When it comes time for maintenance you want to be certain that you can get any part you need when you need it. Many resellers only provideyou the system and leave you in the dark when it comes time for replacement parts.

Here at NU Aqua we take pride in all of our products. We ensure all components in our systems are of top quality, provide the best performance, and offerindustry-leading support, which is why we can offer the industries best warranty at no extra cost.

How much maintenance does a reverse osmosis system require?

Reverse osmosis systems are easy to maintain and require minimal maintenance.

  1. Replacement filters: All reverse osmosis systems require replacement of their filters and membranes. This simple process only takes a few minutes and can be done by anyone. For most systems the pre-filters and post carbon filter require replacement every 6-9 months and the membrane every 1-1.5years.
  2. Annual sanitizing: In order to keep your system clean and prevent contamination it’s best to sanitize your system once a year during your filter change.The process is easy and only takes a few minutes and a few tablespoons of unscented household bleach.

What reverse osmosis filter is best for me?

When it comes to selecting the right reverse osmosis filter for your home the options can be overwhelming. To determine the right system you must first look at where your water comes from. Whether your on municipal city water or your main water source is from a well, this is a big factor in determining which system will work best for you.

Unlike city water that is treated with chlorine, well water is untreated and requires more filtration to be safe to drink. Since well water is direct from the source, your local environment has a heavy impact on the quality of your water. If you live near agriculture or livestock your water can be subjected to nitrates and nitrites from chemical fertilizers as well as bacteria and microorganisms from animal waste. Manufacturing and mining industries can produce waste that leaches heavy metals into groundwater that contaminate your water source. These are just a few of the potential hazards that can contaminant your well water. Depending on your locations there are hundreds of other factors that affect your water.

Some homes that have well water as their source will have a whole house ultraviolet filter in place. If your home does not and you're seeking an additional treatment stage, a UV filter is a popular option. Homeowners on well water sometimes choose to add UV treatment as a supplemental measure.

It's best to have at least a 6 stage system with the ultraviolet filter to have an additional treatment stage for your water. Our UV filters provide supplemental ultraviolet treatment for well water applications.

Regardless if you're on well water or city water, your water pressure is important for a reverse osmosis system to work efficiently. For a reverse osmosis membrane to function properly a minimum water pressure of 40PSI is required. Homes that are on well water often fall below 40PSI and require a system that features a booster pump. If your source of water is from the city your water pressure should be over 40PSI and the use of a booster pump is optional.