Best Tankless Reverse Osmosis System Reviews in 2023

As an Amazon Associate We Earn From Qualifying Purchases.
  • No more waiting around for a tank to fill before consumption!
  • No limit for filtered water!
  • No more stored water contamination!

Yes, you’ve heard that right.

Tankless RO system is a game-changer when it comes to solving the problem of stored water contamination. It’s a great alternative to tanked RO systems.

Direct flow reverse osmosis system is a new technology that filters water instantaneously and sends it directly to the faucet.

However, buying the best tankless reverse osmosis system requires thorough research and testing out the different models. In fact, you need to be extremely sure which system will best serve your immediate and long-term needs.

Unfortunately, you may not have the time or resources needed to carry out that task.


We took it upon ourselves to do the research and testing and provide you with the best RO systems without water tanks.

This tankless reverse osmosis system review showcases five top models on the market right now.

Read on, and we’re sure you’ll find one that best suits your needs.

A Quick Comparison of Our Favorites

Here are the Best Tankless Reverse Osmosis Systems in 2023

The goal of this review post is to recommend you the best options available. Hopefully, you end up making the right purchase on a RO system without water tank that best fits your needs!

1. Waterdrop RO Drinking Water Filtration System, WD-G3-W

Waterdrop WD-G3-W

Top Features

  • Innovative composite filter
  • 7 stage deep filtration
  • Smart leakage protector
  • Real-time water quality display
  • NSF 58 and NSF 372 Certified
  • UL Listed Power
  • Stylish and lead-free faucet included

When buying a no-tank RO filtration system, Waterdrop is a brand that offers exceptional value. Waterdrop is a professional and well-known brand for water filtration system. The WD-G3-W is their one of the best advanced tankless RO systems.

Why is Waterdrop reverse osmosis system number one on our list?

Put simply: the WD-G3-W 7-stage deep filtration does it all. Everything about this RO filtration system makes it well worth.

The multi-stage filtration layers filter water faster and make performance better. Thanks to its high-quality filtration media for a premium effect.

It’s the first RO system with composite filter technology. This innovative technology efficiently filters out more than 1,000 organic and inorganic harmful substances from water while improving the taste of water.

It comes equipped three filters that provide seven stages of water filtration. Its pre-sediment and high-granule carbon filter function as a 3-in-1 filter.

The innovative designed RO membrane’s filter efficiency is more than that of the three stages of filtration. The high-precision activated carbon granules of Carbon block filter return beneficial minerals into the water.

With this seven stages reverse osmosis system you’re getting:

  • First sediment PP membrane to remove rust, sand, particulates, nematodes and suspended substances.
  • Premium carbon block filter for removing limescale, fluoride, lead, chlorine, bad taste and odor.
  • Second sediment PP membrane for targeting additional impurities and supply clean water to the next layer.
  • Three layers RO membrane to trap 99.99% of bacteria, heavy metals and TDS.
  • Post activated carbon block layer to ensure great tasting water.

With filtration accuracy of 0.0001-micron, it effectively removes most contaminants including limescale, TDS, fluoride and heavy metal from tap water.

Moreover, the centralized filtration performance reduces the frequency of filter replacement making it cost-effective.

The no-tank design of this unit eliminates the waiting for tank fill up. It also helps to avoid secondary pollution from filtered stored water. What’s more, its compact footprint allows more storage space in your kitchen.

The system produces pure water quickly and offers faster water flow- 400 gallons per day. It’s perfect to meet the filtered water needs of your whole family, office and even small companies.

Compared to the conventional RO system, this system with 1:1 drain ratio saves water by 300%. Yes, 300. So, it helps you save hard-earned money on your water bills. The integrated water circuit also helps avoid leakage.

It’s not even the best part. There is more.

WD-G3-W is NSF 58 certified for TDS reduction. Its TDS reduction rate is up to 94%. Moreover, it’s NSF 372 certified to ensure lead-free components.

You can install this smart system entirely within three seconds. Yes, installation is that simple! Moreover, you can change the filter with one single turn.

Most importantly, it doesn’t come close to the reverse osmosis system cost what you think it would.

To summarize, Waterdrop WD-G3-W is an innovative, all-in-one intelligent water purification system. It’s perfect to meet the water demands of households and small businesses.

It’d be hard for us to NOT recommend this RO system to you. Seriously, it’s that good—no doubt the best direct flow reverse osmosis system available.


  • Smart, compact design
  • Time-saving and easy installation
  • Multi-stage filtration
  • 3s filter installation time
  • Faster and reliable performance
  • Economical and environmentally friendly


  • It’s relatively expensive compared to others of its class. However, the functionality and design justify this pricing.

2. Frizzlife PD600-TAM3 Alkaline Remineralization RO System

Frizzlife PD600-TAM3

Top Features

  • High-grade RO membrane
  • 0.0001-micron filtration accuracy
  • 2-in-1 composite filter
  • Alkaline remineralization filter
  • LED-free Stainless Steel Faucet
  • Real-time smart TDS system
  • Leak detector and stopper

Frizzlife PD600 is truly a perfectionist piece of equipment. This system delivers a high-quality filtration performance that purifies water better than most RO filtration systems.

What’s great about it?

It’s one of the best tankless alkaline RO systems. You’re guaranteed ultra-pure, clean and safe water for you and your family with this 4-stage RO system. It produces healthiest and most excellent tasting water for you.

In the first stage of filtration, the sediment filter functions as two filters combined. This 2-in-1 composite filter blocks fine debris and reduces large particles. It also Conditions the water and prolongs the service life of the RO membrane.

In the second stage, it uses high-grade RO membrane with 0.0001-micron filtration accuracy. It can trap more than one thousand contaminants from water.

Finally, the alkaline remineralization filter balances the alkalinity of RO filtered water and restores natural minerals. It also reduces odor, bad taste and polishes the water flavor.

Get a full cup of purified water in a snap! It can produce 600 gallons of water per day. And it offers stable water flow. This high capacity can meet the daily water needs of any large family.

And you know what else?

The built-in real-time TDS system is always being updated for every 1 minute to monitor water quality 24/7. What’s more, the color-coded indicator will notify you of the cartridge replacing time in advance.

Importantly, this model comes with leak protector to protect you from leaking nightmare. The reliable leak detector and stopper automatically shut off the power supply in the event a leak should occur to give you peace of mind.

Filter replacement and installation of this unit is a breeze. In a few minutes, you can completely install it. You can change the TAM3 filter without shutting off the power supply.

Frizzlife PD600 is a compact and sleek system with a convenient and small footprint. It takes up less space to safe storage under the kitchen sink.

This model is eco-friendly and money saver! It inaugurates the advanced water-saving technology that maximizes efficiency and water savings. It can save your water up to 450% compared with conventional RO systems. It’ll make your water bills more affordable.

Unlike the traditional all-in-one filter housing, you only need to change the filter cartridge inside that makes it environment-friendly by reducing plastic waste.

To say that Frizzlife PD600 under counter filter system beats other systems by far. It is worth every penny.


  • 50% space-saving design
  • 99.99% contaminants removal
  • Restores health-benefiting essential minerals to water
  • Convenient filter replacement and installation
  • No leak concerns
  • Cost-effective and eco-friendly
  • 3X longer lifespan of the filter and system


  • None

3. Best Tankless Reverse Osmosis System for Well Water: ispring RCS5T Tankless RO Water Filter System

Best Tankless Reverse Osmosis System for Well Water: ispring RCS5T Tankless RO Water Filter System

Top Features

  • 5-stage filtration
  • Patented dual-flow RO membrane
  • Built-in booster pump and
  • Easy-to-read Pressure gauge
  • Clear see-through 1st stage housing
  • Sliver chrome drinking water faucet

The ispring RCS5T is another excellent option on our tankless RO system review. It offers you several additional benefits that make it a standout unit for On-demand drinking water system.

This model is designed to meet the needs of light commercial and high demand environments. So, if you’re looking for a high capacity RO purification system for your home, small restaurants or small business, this is an excellent product for you.

Of course, you can add a holding tank to this ispring RO system to convert it to a whole-house reverse osmosis system for high usage situations.

What sets this system apart from the rest of the crowd?

RCS5T eliminates the need for a storage tank without affecting functionality or convenience. Conveniently, the 1st stage housing is see-through clear that makes filter inspection a snap.

RCS5T offers an unmatched five-stage filtration.

  • PP sediment filter to trap larger particle such as dirt, rust and sand
  • GAC filter to absorb chlorine, odor and discoloration
  • Carbon block filter to remove any residual chlorine and improve the water taste
  • Advanced dual-flow RO membrane for eliminating viruses, bacteria, heavy metals and other harmful substances.
  • Post carbon filter to improve the quality of reverse osmosis drinking water.

One of the outstanding features of this five-stage RO system is its dual-flow membrane. It receives water from both sides of the membrane housing. It helps to save 70% more water than a regular RO membrane.

You don’t need to be worried about low water pressure. It comes equipped with a high-power booster pump that maximizes purified water production by increasing water pressure.

However, you can use the system with water pressure sources as low as 25psi. There is also a built-in- pressure gauge to ensure accurate pressure reading.

To sum it all up, ispring water system RCS5T is a robust, and reliable product for large families and light commercial use. We would strongly recommend as a must buy if it meets your needs. You’re sure to get your money’s worth with this model.


  • High capacity
  • Excellent efficiency
  • Low waste of water
  • Cost-effective water usage
  • Fairly easy to set up and filter replacement
  • Excellent customer service


  • No indicator for filter life

4. GREATWELL ROG400 RO Water Filtration System

GreatWell ROG400

Top Features

  • 3-stage filtration
  • PAC composite filter
  • Filter change indicator
  • 1-year limited manufacturer warranty
  • Faucet included

GREATWELL ROG400 is a new generation RO water filtration system and one of the best home drinking water filtration unit available. It comes with many impressive features.

First of all, it has a unique looking that makes it stand out from other filtration systems. For those who don’t know, this advanced filtration system is the winner of Deutsch iF design award.

No matter you have bad tasting water or safety concern, the GREATWELL ROG400 is the ultimate solution of your home drinking water problems

The ROG400 effectively eliminates more than 1,000 different types of pollutants from your drinking water. Thanks to its precision RO technology.

The best part of this model is the PAC composite filter. It’s actually a 3-in-1 carbon block filter that works as a combination of 2 PP sediment filter and a carbon filter.

The RO membrane provides up to 40 oz of purified water within a minute.  This three-stage filtration process effectively filters out up to 99% of over 1000 contaminants.

The activated carbon filter further polishes the water to deliver odorless, high-quality, excellent tasting drinking water.

This unique filter combination saves more than 30% of the space within the unit. It also reduces the filter replacement cost in the long term.

The 400GPD fast water flow is guaranteed. Thanks to its built-in booster pump and GE RO membrane. The 1.5: 1 drain water ratio will help you to cut down the water bill and save the environment.

DIY installation of this model is super easy. The thoughtful route design simplifies the installation process. It’s worth noting that traditional RO system has more than 30 connectors, but this unit only has eight connectors on the board.

The tankless and all-in-one space-saving design provides more under-sink or countertop free space.  You can also connect the unit to the refrigerator or ice maker. It also removes leaking concern.

What’s more, it has a built-in true filter change indicator that individually monitors each filter’s life.

The 304 stainless steel inner tube is lead-free which dispenses drinking water safely through the faucet. Importantly, ROG400 uses FDA-approved premium-quality components in all parts.

Overall, GREATWELL ROG400 is an outstanding product. The purification level of this unit will exceed your expectations!


  • Premium components
  • Super filtration results
  • 1000+ contaminants removal
  • Compact and space-saving
  • Simple installation process


  • For connecting it to the refrigerator/ice maker, you’ll need to buy some extra lines.

5. SimPure Q6 Reverse Osmosis Filtration System

SimPure Q6

Top Features

  • 3-in-1 PP&CTO composite filter
  • Snap-on filters design
  • FCC/UL Listed
  • Smart Light Reminder
  • Lead-free Faucet
  • Filter change indicator on the faucet

The SimPure Q6 is a next gen RO water system. It’s an innovative and intelligent water purification system that helps you make life simpler and easier.

It’s the definition of a budget-friendly RO system. It just does so much; you can’t beat it. I mean seriously?

With 0.0001 microns filtration accuracy, this 4-stage filtration system can effectively remove more than 1000 water pollutants.

This system contains:

First Sediment PP membrane to trap dirt, sand, rust and dust

High precision activated carbon block to remove limescale, chlorine, fluoride, TDS, lead and other radioactive substances

Second sediment PP membrane for eliminating particle, sediments and nematodes

RO filter to remove bacteria, viruses, organic matter, heavy metals and other harmful substances

At 400 GPD, it offers faster water flow providing a cup of 5 OZ filtered water within 9 seconds.

The no-tank design helps you to avoid secondary pollution from the reservoir and provide fresh water instantly. Moreover, it’s compact that saves 70% of your under kitchen space.

Filter replacement is super easy. You’ll need only 5 seconds to get the job done. Conveniently, there is an indicator on the faucet that lets you monitor the filter status easily.

It’s worth noting that PPC filter cartridge replacement cycle is 1 year and that of for RO filter cartridge is 2 years. Compared to the traditional RO system, it saves the replacing filter costs for 5 or 6 filters.

All things considered, the SimPure Q6 is worth considering if you are in the market for a budget-friendly RO system. While it doesn’t have a lot going for it, it’s decently priced.

Seriously, it’s an excellent pick for anybody on a tight budget. It’s long-lasting and easy to maintain over the long run.  Enjoy purer and cleaner water at lower costs with this RO system.


  • Innovative and Intelligent design
  • Compact and simple to install
  • Long-lasting and easy to replace the filters
  • Smart & easy to use
  • Quite budget-friendly
  • Two years warranty and lifetime tech support


  • You’ll need a particular hole to install the included faucet in your countertop.

Advantages of Tankless Reverse Osmosis Filters

Best Tankless Reverse Osmosis System

Direct flow RO system offers premium water while saving space. Due to no-tank design, this type of filtration system won’t take up as much space as traditional reverse osmosis water filters.

For household with limited space, it’s an excellent alternative to traditional RO systems.

And you know what else?

  1. The system uses multiple membranes that efficiently purify water. Due to improved contaminant rejection rate, it offers better water purification quality.
  2. It doesn’t require prolonged timeouts to fill the tank with filtered water. No tank means no waiting for water to get filtered – it’s an instant filtration and delivering process.
  3. The system is capable of producing on-demand and unlimited pure water in real-time. While traditional RO tank systems are limited by the reservoir capacity, a tankless system is limited by the filtration rate of the membrane only.
  4. As it doesn’t depend on how full the tank is, it works well even at low-pressure water (below 40 psi). It offers sustained, and instant filtered water flow and also increases the water pressure up to 100 psi.
  5. In the RO filtration system with tank stores water which after a while may get a bad taste. But filtered water with tankless RO system eliminates any pollution from lengthy water storage. And the filtered water tastes better than stored water.
  6. It includes a powerful pump that helps to reduce wastewater. Due to the much higher efficiency rate, compared to the conventional tank system a no-tank model wastes three lime less filtered water per gallon.
  7. Due to long service life of membrane and pre-filters, tankless systems cost less, which in turn results in a higher efficiency rate.
  8. It has a less frequent change in the necessity of filters. What’s more, it features less number of components than a tanked system which leads to easier servicing and better reliability.

Tankless RO Filter – How does it Work?

This type of system works pretty much the same way as a RO system with a tank. The most noticeable differences are tankless design and the number of RO membranes.

Traditional RO filtration system features single RO membrane. But tankless units come equipped with multiple pre-filters that helps to deliver a more efficient filtration.

Tankless filter dispenses water immediately through the faucet. The efficiency of all types of RO system depends on the incoming water pressure. A reverse osmosis membrane works effectively when it works under high pressure.

So, if the incoming water pressure doesn’t meet the required value or less than 40 psi, you may need to add a booster pump- no matter it’s a tankless or tanked RO system.

Things to Consider When Buying

So, you’ve figured out a tankless RO system is the best option for you. Great!

But what is the next thing?

There are some factors that you should put into perspective.

Here are the factors to look out for-

GPD (Gallon per Day)

When deciding to buy a model check that its flowrate or GPD is perfect to meet your all water needs. The higher the flow rate, the better the system is. But buying a system with higher GPD for a small family would be a waste of money. So, we recommend purchasing one that best suits your household needs.

Ease of installation

Ensure that the model you’re going to buy is easy to install. Make sure the installation instruction is clear and provides a well-labelled diagram. Having an instructional video is a plus for DIY installation.

Drain Ratio

Check out the system purified water to the maximum. And it doesn’t waste too much water.

Filter life and system durability

Confirm how long it takes before replacing the filters and membranes. Also, check the component’s quality to ensure the system’s durability.


Different manufacturers offer different warranties on their RO systems. The most common warranty period is one year. However, many come with a money-back guarantee of the month. We advise you to check the warranty when purchasing a system.

The Price

Tankless systems are undoubtedly more expensive than regular RO filters. It’s also worth noting that some no-tank models deliver better-filtered water than ordinary tanked RO filters. This advantage is well worth the higher price tag.

When quality is of concern, the price may be overlooked. However, you should compare the reverse osmosis system prices of different models. Don’t overpay just because the manufacturer says the system is good.


Is a no-tank reverse osmosis system worth investment?

If you greatly value immediately filtered water and space-saving solution, a no-tank model might be a worthwhile investment for you. On the other hand, if instantly filtered water and space are not on the top of your consideration, a RO system with a tank will be just as good as a tankless one.

Can I install a tankless model myself?

Yes, this type of systems is becoming increasingly popular for self-installation. If you’re somewhat mechanical and handy and feeling confident installing tankless models won’t be too difficult or time-consuming.

Is it essential to have a water softener for reverse osmosis?

Absolutely. In fact, a water softener helps to protect the RO membrane that makes it last longer.

Which is better- a RO system or water softener?

In fact, it depends on your water treatment needs. A RO filtration system not only filters but also softens water. But if it constantly filters the hardest water, the RO membrane may wear out faster.

If you have severe water hardness problem, it’s economical to soften the water before it enters the RO membrane.


Our journey of the best tankless reverse osmosis system coming to an end.

The road to getting healthy and tasty drinking water is a fast and simple one. All that you need is a no-tank RO system.

Before making this shortlist, we’ve taken each system through a series of test to make sure it’s really top-notch.

So, you can rely on our review to pick the best one from our list to meet your needs.

Use tankless RO water filtration system, save money, save environment!

Leave a Comment