6 Best Tankless Reverse Osmosis Systems in 2022

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Imagine having access to purified drinking water right by your kitchen sink at a very affordable price. An initial investment in the best tankless reverse osmosis system can help you cut down future costs of having to buy bottled water every now and then.

What’s more, aside from easy access to filtered water, you can have more space in the kitchen compared to if you have a bulky water dispenser.

We understand that it’s not easy to find the right product, though. For this reason, we took it upon ourselves to narrow down the options to only the best of the best. Read through the best tankless RO water filtration system reviews below to find which one fits your kitchen the most.

Our Top Picks Compared

Best Tankless Reverse Osmosis System Reviews

Each kitchen is unique, and we all have our preferences. So, if you are looking for the best reverse osmosis filter, the best choice is one that should fit all your requirements.

The following list outlines the six top-rated no-tank RO water filters available in the market, along with the features of each. You can trust that each one underwent rigorous testing and is sure to deliver more than what’s promised.

1. Waterdrop WD-G3-W Reverse Osmosis Drinking Water Filtration System

Water quality is the focus of Waterdrop, a trusted brand in water purification solutions. Their aim is to deliver clean and healthy drinking water to every home.

Founded in 2015, Waterdrop has manufactured around 200 types of water purification products, and the Waterdrop WD-G3-W Reverse Osmosis Water Filtration System is only one of their best creations.

Here are its best features:

  • Seven stages of filtration
  • NSF 58 & 372 certified
  • Embedded smart design and functionality
  • Water flow rate at 400 gallons per day or approximately 1 liter per minute
  • Protection technology
  • 1:1 low drain ratio saves water
  • Easy installation, quick-change filter cartridges

Three Filter Cartridges, Seven Stages of Filtration

The Waterdrop WD-G3-W RO Filter System boasts two layers of polypropylene (PP) cotton, two premium carbon blocks, and three reverse osmosis membranes.

The first filter cartridge has a carbon block in between two PP cotton layers. The PP cotton layers remove nematodes, rust, sand, and large particles, while the carbon block layer removes lead, fluoride, chlorine, tastes, and odors.

The second cartridge is the RO cartridge. It is built with the patented DOW reverse osmosis membrane with three layers capable of removing PFAS, minerals, and TDS.

An additional activated carbon block cartridge is the seventh stage of filtration. Made from Sri Lankan coconut shells, this added carbon block improves the taste of your filtered water.

Innovative Design and Functions

Would you want to know when to replace the filter cartridges on your RO setup? Look no further, as the Waterdrop WD-G3-W comes with an outlet faucet that has a LED indicator. The LED light changes color depending on the status of the filters.

The device’s front panel also has a TDS counter, which reads total dissolved solids filtered in real-time.

Other smart design functions include automatic flushing, embedded sound indicators, and holiday mode.

Safety for Your Convenience

All waterways are embedded in this device to remove the risk of leaks and water waste. Materials used are insulated to protect against freezing and overheating.

If used continuously, the device reminds you when the booster pump is overworked. When there is no water or a water shortage, the device also informs you about the problem. Wouldn’t you like that smart design for instant filtered water?


  • Smart, innovative design
  • Easy installation
  • Water-saving
  • Most filtration stages
  • Compact system, all components in a single housing


  • Slightly more expensive than other brands and models

2. Frizzlife PD600-TAM3 Reverse Osmosis Water Filtration System

The goal of Frizzlife is to deliver the most efficient, durable, affordable, and eco-friendly water solutions to every family. They believe that if you want to start a pure life, you should start with pure water in the home.

One of their most effective and efficient water purification solutions for the home is the Frizzlife PD600-TAM3 Reverse Osmosis Under Sink Water Filter System.

Its top features are:

  • 6-stage filtration
  • Alkaline remineralization
  • Under-sink installation saves counter space
  • Quick-change filter cartridges
  • 600 gallons per day high water flow
  • 1.5:1 efficiently low drain ratio
  • Smart LED display

RO Membrane Removes up to 99.99% Contaminants

Equipped with six stages of filtration, the Frizzlife PD600-TAM3 uses three huge filter cartridges.

The first and second stages are both combined in the first filter – it blocks microorganisms and fine debris. It reduces particles in the water while conditioning it to prolong the reverse osmosis membrane service life.

Reverse osmosis occurs in the second filter, where most contaminants, minerals, and chemicals get separated from the water. The main system houses both the first and second filter cartridges.

The third filter is positioned in a separate cartridge outside the main system housing, and it completes the three final stages: taste, alkalization, and mineralization (TAM3).

You will be happy to know that Frizzlife ensures to reduce bad taste and odor and polish flavor with this filter. With the TAM3, restore essential minerals and balance water alkalinity by increasing its PH to more than 7.5.

Efficiency, Affordability, and Technology

The Frizzlife PD600-TAM3 offers a 1.5:1 low drain ratio that saves water up to 450% at a very affordable price. Your initial expenses will surely be an excellent investment into a long-life water purification solution.

The system boasts a 600-gallon per day high water flow rate, and you’ll be amazed how it can fill a 330ml cup in just 10 seconds!

With a smart LED display, the Frizzlife PD600-TAM3 indicates each filter’s remaining lifespan, and it also shows real-time TDS counts. It can continuously monitor water quality by reminding you to change filters in advance using its color-coded indicators.

You can easily remove the filters with its canister twist design. You won’t be needing tools, and you can replace the filters in a breeze.


  • High water flow rate
  • Space-saving
  • Up to 450% water savings
  • More affordable than other models
  • Alkalization and remineralization
  • Quick filter replacement


  • Bulkier than other brands, has an extra cartridge other than main housing

3. iSpring RO500 Tankless Reverse Osmosis Water Filtration System

You will also want to consider products from iSpring Water Systems. They are a company that makes both residential and commercial grade reverse osmosis systems, apart from other plumbing filtration products.

One of their sleekest RO systems is the iSpring RO500 Tankless Reverse Osmosis Water Filtration System. It features simplicity at its finest with its compact housing, minimal connectors, and quick and easy installation process.

Let’s look at its best features:

  • Excellent filtration performance
  • Five stages of filtration
  • Quick and easy installation
  • 2:1 pure-to-waste ratio
  • Real-time monitoring of TDS
  • Purifies 500 gallons per day
  • Filter status indicator

New Generation RO Filter

The iSpring RO500 Tankless RO System raises the bar using the latest technology in reverse osmosis for water purification and filtration. Distributed into three filter cartridges, the five stages of filtration removes up to 99% of contaminants.

The first filter is a 3-in-1 multi-layer composite filter that removes sand, dirt, rust, and other particles along with chlorine and unpleasant odors.

The next filter is a 500GPD high-flow RO membrane that can remove 1,000+ contaminants, including arsenic, lead, asbestos, lead, fluoride, and many others from the water.

The final filtration stage uses a carbon block that can give you purified, tasty, and odorless drinking water.

Hassle-free DIY Installation and Replacement

Aside from its no-tank design, a compact housing encloses the iSpring RO500 components. It saves a lot of space under the sink. All included connectors are integrated into the housing to simplify the installation process and to eliminate leaks.

Like the Waterdrop WD-G3-W, the iSpring RO500 has a front panel with three knobs – one for replacing each of the three filter cartridges. You’ll find it very easy to replace those filters in no time. Position your iSpring RO500 on a flat corner under your sink, with its knobs facing outward for easy future replacement of all the filters.

Advanced Filtration and Detection Technology

The iSpring RO500 has a 2:1 pure-to-waste water ratio that means it can produce two glasses of water while only expelling one glass of wastewater.

It has an embedded real-time TDS monitor that works with a filter status indicator to tell you when you should be replacing your filters.


  • Smart protection against leaks
  • 0.4 GPM fast flow rate
  • Sleek, space-saving design
  • Lifetime support within the USA
  • 30-day money-back guarantee
  • Continuous instant filtered water supply


  • Not designed for well water
  • Requires pre-treatment devices for groundwater and well water sources

4. GreatWell ROG400 Tankless Reverse Osmosis Water Filter

GreatWell manufactures a wide array of products that can make your home more efficient and more comfortable. From kitchen utensils to mattresses, they design items that can make your life a lot easier.

GreatWell also specializes in water purification for homes, and they have done well by designing the GreatWell ROG400.

Let’s have a look at its features:

  • 5-stage filtration
  • 400 gallons per day flow rate
  • Vertical filter cartridges
  • Snap-on connections
  • Tested against NSF/ANSI standards
  • Gold metallic finish
  • 1.5:1 low drain ratio

Easy-Install Innovative Design

The GreatWell ROG400 Tankless RO Water Filtration System has upright filters inside its housing unit – this makes the device occupy less horizontal space under the kitchen sink. In addition to this, the device uses snap-on connections for easier installation and replacement of filters. You can remove a side panel to replace the filters.

With its gold metallic exterior finish and curved tapering edges, the GreatWell ROG400 has a unique appearance. You won’t find any protrusions on the sides as most of the indicators and hose connectors are on top of the device.

Three Filters, Five Vital Stages

The first filter inside the GreatWell ROG400 combines three filtration stages into one inside its PAC composite filter. The 3-in-1 combo makes the whole system more compact, and it occupies so much less space. The PAC filter combines two polypropylene sediment filters with one carbon filter in between.

For the second filter, the GreatWell ROG400 uses a reverse osmosis membrane that is rated to transfer 400 gallons of water per day – which means you can have 40 ounces of clean water in just under one minute! The RO membrane removes over 1000 types of contaminants and can last for up to three years.

The third and final filter on the GreatWell ROG400 uses an activated carbon filter to produce polished water that is clean but tasty and odorless.


  • Efficient and elegant design
  • Component materials are FDA-approved
  • Saves more space
  • Individual indicators for each filter
  • Leak-proof connections


  • Indicators not directly visible from in front of the device

5. iSpring RCS5T Commercial Tankless Reverse Osmosis Water Filter System

iSpring Water Systems also create great products for larger families, restaurants, and small businesses. One of these products is the iSpring RCS5T Commercial Grade Tankless RO Water Filter System.

Here are its top features:

  • Produces 500 gallons of clean water per day
  • Patented dual-flow RO membrane
  • 1:1 low drain ratio
  • Five filtration stages
  • Powerful booster pump
  • 24/7on demand production

Large Residential or Small Commercial Use

The iSpring RCS5T has a remarkable ability to thrive without a bladder tank. You can add a small pressurized tank to increase the water flow rate without sacrificing so much space in large residential applications.

For restaurant use, pair the iSpring RCS5T with a medium-sized pressure tank to supply round-the-clock filtered water that can keep up with all your business demands.

The iSpring RCS5T has a built-in pressure gauge, and you can pair it with pressure systems having outputs as low as 25 psi.

5-Stage Filtration with Dual Flow RO

The iSpring RSC5T comprises five filter cartridges and a booster pump; all assembled onto a metal stand frame.

Before passing or getting sucked through the booster pump, water passes through three vertical filters: a sediment filter, a granular activated carbon (GAC) filter, and combined chlorine, taste, and odor (CTO) filter.

The booster pump then transfers the water into the horizontal RO filter on both sides, making it a dual flow RO, and permitting instant, 24/7 on-demand filtered water supply.

Finally, after the RO membrane, water travels to a post-carbon filter, which re-mineralizes your water for a better, odorless taste.

If you have a large family or plan to put up a small restaurant, the iSpring RSC5T can be your best option.


  • Great for large residential or small commercial applications
  • RO membrane filter lifespan rated up to 2600 gallons
  • 750 ppm maximum TDS
  • Can withstand water pressures up to 70 psi
  • Operates within a water temperature range of 40 to 100 degrees Fahrenheit


  • Much more expensive than other models discussed here
  • An unsightly device, no housing

6. Purlette PL400G Hybrid Reverse Osmosis Water Treatment System

Purlette believes that there is always a better way to improve water quality – they design unique filtration systems for the home using all available technological advances. Their mission is to bring elegant, convenient, and innovative water treatment solutions into every home.

At Purlette, they have created the PL400G Hybrid Reverse Osmosis Water Treatment System. It is their crown jewel, and it is the first smart technology hybrid water purifier for the home.

Here are the features that make it so innovative:

  • Tankless and space-saving design
  • Five stages complete all-in-one filtration
  • 2-filter design
  • Partner mobile application for real-time monitoring
  • Easy installation and maintenance
  • Produces 400 gallons of clean water per day
  • UL, WQA, and FCC tested
  • Real-time monitoring of TDS

4-in-1 Hybrid Filter + RO Filter

The Purlette PL400G only uses two filters.

The first filter is a hybrid cartridge, which combines four stages into one container. This filter removes suspended particles, eliminates odors and flavors, and stops scaling.

After passing through the hybrid filter, water gets drawn into the RO filter, which has a capacity of 400 gallons per day. The reverse osmosis removes 99% of over 1000 common contaminants in water, which include harmful minerals. This RO filter can last up to 24 months.

After passing through the RO filter, water in the system passes through the hybrid filter for a second time to complete the final filtration step.

With this device, you will only be needing three filters within two years – one RO filter and two sets of hybrid filters.

Smart Home Ready

The Purlette PL400G is the very first smart home ready reverse osmosis water purifier. It comes with a mobile application downloadable from the internet.

This application provides you with real-time 24/7 monitoring to check the quality of your drinking water and track the operational life of your two filters.

You also have the option to get the Purlette Amazon Alexa Skill, so you can use your voice to do the same maintenance tasks remotely.

In addition to all of these smart applications, you can order replacement filters right from your mobile device!


  • Smallest compact design
  • Cheapest among the bunch
  • BPA and lead-free
  • The hybrid filter can last 12 months
  • RO filter can last up to 2 years
  • Includes lead-free drinking faucet
  • Alerts for high TDS


  • Not suitable for well water, may require well water treatment

What is reverse osmosis?

Reverse osmosis (RO) is a process that devices use to purify water. This process employs a semi-permeable membrane to remove particles in drinking water, such as unwanted ions, molecules, and visible sediments.

What is a tankless RO water filtration system?

A reverse osmosis water filtration system has several partially permeable membranes, each designed to remove a specific type of particle suspended in water. Water has numerous impurities. The more semi-permeable membranes included ensures that most unwanted particles are removed from drinking water.

Although a tankless RO system is more expensive than one with a tank, it provides instant filtered water with very little space use. If you are looking for an efficient way to instantly filter your water without using so much space, a tankless RO system is a way to go!

What are the unwanted particles in water?

As water travels from reservoirs and desalinization plants to your home, it can accumulate minute particles, substances, and organisms that can be harmful to your health.

These unwanted particles include bacteria, nematodes (parasites), rust, sand, dirt, naturally occurring minerals, manmade chemicals (polyfluoroalkyl substances or PFAS), and total dissolved solids (TDS).

What are the benefits of a No-Tank RO Filter System?

A no-tank RO filter system is one of the best solutions for water purification, and here’s why:

A. Prevents Secondary Pollution

Secondary pollution occurs when there is stagnant water, even in a closed container. Bacterial growth and accumulation can occur within a water reservoir or bladder tank. You can prevent this with the use of a no-tank reverse osmosis system.

B. Saves Space

Another benefit of having a tankless RO system is more space. You can have a cheaper, unsightly RO system that has a large tank, or you can have more space on your countertop or under your kitchen sink if you get one that has no tank.

C. Promotes Environmentalism

In addition to these benefits, you will be saving the environment using a reverse osmosis filtration system. You won’t have to stock up empty plastic bottles because you won’t be needing to buy bottled water.


Given the choices, the best rated tankless reverse osmosis system has advantages over the traditional RO systems with tanks. A no-tank RO system eliminates the need for more space, and it provides instant filtered water.

Get rid of all the unwanted particles in your drinking water with a choice from these top options. We have listed each product with its own merits to help you understand what suits your preferences. Each product has been tested for quality performance, and you won’t have to worry that your choice is a bad one.

Replace your old habits of purchasing bottled water, and start saving the environment by shifting to a tankless RO filter now!