Tankless RO Systems: Top Picks, Reviews & Buying Guide

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Looking to buy a Tankless RO System?                                           

You’ve come to the right place!

Tankless reverse osmosis systems provide on-demand 100% purified water, making them one of the safest water sources you can use in your home.

Unlike RO systems that use tanks, these models take up very little space.

Despite their compact size, the efficiently eliminate up to 99% of contaminants in your water, neutralize foul odors, and improve the overall taste and quality of your water.

But which tankless reverse osmosis system is right for your needs and budget?

Let’s find out!

What’s In This Buying Guide

This buying guide recommends, reviews, and compares the best tankless RO systems available on the market.

We also discuss the critical features & gotchas to consider before purchasing a tankless water filter.

Near the end of this article, we answer some of the most frequently asked questions about tankless water filter systems, so you can easily make a well-informed decision.

So let’s get started with our top 3 favorite tankless systems (all sold online):


Best Tankless Reverse Osmosis Systems

Disclaimer: All links below go to Amazon.com

  1. Most Durable: Waterdrop WD-G3-W
  2. Best for Large Families: Frizzlife PD600-TAM3
  3. Easiest to Maintain: Waterdrop WD-G2P600-W
Title
Waterdrop G3 Reverse Osmosis System, Tankless RO Water Filtration...
Frizzlife RO Reverse Osmosis Water Filtration System - 600 GPD...
Waterdrop Reverse Osmosis System, Tankless Ro Water Filtration...
Waterdrop G3 Reverse Osmosis System, Tankless RO Water Filtration...
Frizzlife RO Reverse Osmosis Water Filtration System - 600 GPD...
Waterdrop Reverse Osmosis System, Tankless Ro Water Filtration...
Award
Most Durable
Best for Large Families
Easiest to Maintain
Flow Rate
400 GPD
600 GPD
600 GPD
Drain Ratio
1:1
2:1
2:1
Filters
3
3
2
TDS Display
Yes
Yes
No
Requires Electricity
Yes
Yes
Yes
Dimensions
18.12 x 5.67 x 17.72 inches
18 x 17.6 x 15.6 inches
2:1
Title
Waterdrop G3 Reverse Osmosis System, Tankless RO Water Filtration...
Waterdrop G3 Reverse Osmosis System, Tankless RO Water Filtration...
Award
Most Durable
Flow Rate
400 GPD
Drain Ratio
1:1
Filters
3
TDS Display
Yes
Requires Electricity
Yes
Dimensions
18.12 x 5.67 x 17.72 inches
Title
Frizzlife RO Reverse Osmosis Water Filtration System - 600 GPD...
Frizzlife RO Reverse Osmosis Water Filtration System - 600 GPD...
Award
Best for Large Families
Flow Rate
600 GPD
Drain Ratio
2:1
Filters
3
TDS Display
Yes
Requires Electricity
Yes
Dimensions
18 x 17.6 x 15.6 inches
Title
Waterdrop Reverse Osmosis System, Tankless Ro Water Filtration...
Waterdrop Reverse Osmosis System, Tankless Ro Water Filtration...
Award
Easiest to Maintain
Flow Rate
600 GPD
Drain Ratio
2:1
Filters
2
TDS Display
No
Requires Electricity
Yes
Dimensions
2:1

Most Durable: Waterdrop WD-G3-W

best tankless reverse osmosis system

The Waterdrop WD-G3-W is a smart, innovative, and all-in-one RO filtration system.

It’s the first reverse osmosis unit in the US that uses composite filters in a tankless design.

The WD-G3-W boasts a flow rate of up to 400 GPD and has NSF 372 and 58 certification, meaning it can eliminate up to 94% of dissolved solids.

Features

  • Certified with NSF 58 for TDS (total dissolved solids) reduction
  • NSF 372 certified for lead-free water
  • Uses new composite filter element technology
  • A fast flow rate of 400 GPD
  • 3 filters offer 7 filtration stages
  • 1:1 low drain ration

Our Review

The Waterdrop WD-G3-W is one of the most powerful RO systems available today. It features an impressive flow rate of 400 gallons per day, which is 5x more than a typical home RO filter.   

Moreover, its 7-stage filtration process is NSF certified, and its compact tankless design fits wonderfully under your sink. The unit also features carbon filters to purify your water on-demand, eliminating the need for waiting for the storage tank to fill up.

The WD-G3-W’s pre-sediment filter does the work of 3 different filters combined, while its innovative reverse osmosis membrane filter boasts an efficiency that’s equal to more than 3 filtration stages.

Additionally, its activated carbon block filter features high-precision activated carbon granules that improve the taste of your tap water.

These 3 filters and 7 filtration stages remove chlorine, solids, sand, rust, odor, and other impurities from your water. The WD-G3-W also filters out up to 94% of TDS and reduces bacteria, viruses, heavy metals, limescale, and more than 1000 other dangerous contaminants present in your water.

Thanks to the WD-G3-W’s internal pump, the RO filtration system offers a fast flow rate of 400 gallons per day. In other words, it can purify a cup of water in just 12 seconds, making it perfect for families and even small companies.

With a 1:1 drain ratio, the WD-G3-W is one of the most efficient RO systems available in the market today.

It also features a smart designer faucet with a color-coded LED ring at its base that indicates water quality and informs you when it’s time to replace the filters. A TDS monitoring panel further allows you to see how clear your water is at a glance. 

The Waterdrop WD-G3-W RO filtration system boasts several other smart features that enhance its durability. If the system keeps running for over 2 hours, it automatically flushes the surface of the RO membrane for 20 minutes.

And, if the RO filter does not dispense water for 24 hours, the unit automatically flushes the membrane for 1 minute. This function helps ensure a clean filter and safe drinking water.

The WD-G3-W also helps reduce the chances of leaks. Conventional RO filtration systems have more connections, tubing, and other components that are susceptible to leaks.

However, this is not a problem with this model because its ‘smart leakage protector’ automatically shuts off the power and water supply if it detects a leak. And to fix it, you just need to pull out and clean the water container before reinstalling it.

The Waterdrop model further reduces safety risks and extends the pump’s life by alerting you if you forget to close the faucet. It beeps for three minutes if it dispenses water for over 30 minutes and then automatically stops dispensing water. You just need to restart it for normal use.

The Waterdrop WD-G3-W also boasts protection against frequent and improper start and stop operation. The buzzer alerts you by beeping 5 times and then automatically stops dispensing water. You can resume the system’s operation by simply powering it back on.

However, the Waterdrop WD-G3-W is not suitable for well water because of its complicated composition. The system also lacks a remineralization stage, which can be a big drawback for some.

Pros

  • Tankless and compact design
  • Low drain ratio and high flow rate
  • Saves space under the sink
  • Filters out 94% TDS and other harmful water contaminants
  • Easy installation and straightforward maintenance
  • NSF certified
  • Beautiful design compliments almost every décor

Cons

  • Does not have water remineralization
  • Needs electricity to operate

Best for Large Families: Frizzlife PD600-TAM3

best tankless reverse osmosis system

The Frizzlife PD600-TAM3 can deliver up to 600 gallons of clean water every day, making it ideal for large families. It also balances water alkalinity and adjusts its pH to higher than 7.5 to replace some of its lost minerals and improve its taste.

Features

  • A high water flow rate of 600 GDP
  • Adjusts the pH of RO water and balances its alkalinity
  • Low drain ratio of 1.5:1
  • Smart LED display shows real-time TDS
  • Saves up to 450% more water than traditional RO filter systems
  • Color-coded indicators inform you when it’s time to change filters
  • It comes with a 600G RO membrane and a TAM3 Alkaline Remineralization filter

Our Review

Traditional RO systems produce water that’s slightly acidic and lacking in natural minerals. But you won’t have to worry about this problem with the Frizzlife PD600-TAM3.

The PD600-TAM3 under-counter filter boasts a high-grade RO membrane with around 0.0001-micron filtration accuracy. Its 3 effective filters further purify water by passing it through 7 filtration stages.

The 3-in-1 composite filter blocks fine debris and eliminates particles like silt, rust, sand, and other insoluble impurities. It also conditions the water and extends the service life of the unit’s RO membrane.

The high-grade 0.0001-micron RO membrane eliminates up to 99.99% of contaminants, including lead, fluoride, chloramine, chlorine, heavy metals, mercury, arsenic, VOCs, and much more.

The third filter is an alkaline remineralization filter that balances the alkalinity of the water, adjusts its pH to higher than 7.5, and restores beneficial natural minerals. It also reduces odors and bad tastes and polishes the flavor, ensuring that you only get the healthiest and most delicious water.

The Frizzlife PD600-TAM3 boasts a sleek and compact filter system that takes up very little space.

Its small and convenient footprint helps save space under the kitchen sink, while its tankless design eliminates the problem of secondary pollution. This further ensures that you and your family only get safe, clean, and ultra-pure drinking water.

The internal pump of this Frizzlife model can purify 600 gallons of water per day, making it perfect for the daily water needs of large families. The water flow is fast and stable as well, and you can easily fill a 330ml cup of water in just 10 seconds.

The PD600 helps save up to 450% more water than traditional RO filtration systems thanks to its advanced water-saving technology and low drain ratio. Its environment-friendly and economical design further reduces your water bills, and over time, enables it to pay for itself in water savings.

The PD600-TAM3 also comes with a smart display panel that shows TDS in real-time, along with the remaining lifespan of every filter. Its built-in TDS system continuously keeps track of the quality of your drinking water.

The color-coded indicators also act as an intelligent reminder, informing you when it’s time to change the filters.

The Frizzlide PD600-TAM3 comes with a tutorial video and an instruction manual, so you can easily install the reverse osmosis system by yourself in just a few minutes.

Filter replacement is incredibly easy as well. You can replace the first two filters by simply twisting them after turning off the power supply. In order to change the TAM3 filter, you don’t even need to turn off the power supply.

Pros

  • Filters are easy to change
  • Integrated water line eliminates leakage issues
  • Installation is simple and requires only minimal tools
  • Improves the taste of tap water
  • High GPD capacity 
  • Affordable replacement filters
  • Removes contaminants bigger than 0.0001 μm
  • Incredibly low wastewater production

Cons

  • Produces a humming sound when purifying water
  • The faucet dispenses water at a fast rate only
  • It does not work during power outages

Easiest to Maintain: Waterdrop WD-G2P600-W

best tankless reverse osmosis system

The Waterdrop WD-G2P600-W is basically an upgrade to the G2 (WD-G2-W). Its effective 2-filter design makes it the most affordable and easiest to maintain tankless reverse osmosis system on our list.

Features

  • CF filter uses an activated carbon block and a sediment PP membrane
  • 0.0001-micron RO membrane filters out tiny contaminants
  • A fast water flow rate of 600 GDP
  • Drain ratio of 2:1
  • It helps save 600% more water than conventional RO water purifiers
  • It comes with automatic water shut-off valves
  • It does not make more than 55dB of noise
  • Filter life indicators remind you to change the filters in advance
  • Saves 70% of under-sink space 

Our Review

Boasting an improved composite filter technology, the Waterdrop WD-G2P600-W can remove most contaminants from your tap water. Its CF filter uses an activated carbon block and a sediment PP membrane to remove sediment, organic matter, and rust.

Meanwhile, its MRO filter employs a sediment PP membrane, a PET pleated membrane, a 0.0001-micron reverse osmosis membrane, and an activated carbon block to eliminate atrazine, nitrates, fluoride, heavy metals, TDS, salt, and PFAS from your water.

The WD-G2P600-W can filter 600 gallons of water per day. It provides a stable and fast water flow rate, which is perfect for drinking and washing vegetables and fruit. This model can also fill a 200ml cup in just 8 seconds, making it 12 times more efficient than conventional reverse osmosis systems.

This Waterdrop unit reduces your filter replacement cost and adopts water-saving technology. It boasts a drain ratio of 2:1, which basically means that you get 1 cup of wastewater for every 2 cups of filtered water.

The G2P600 RO system saves 600% more water than traditional RO filtration systems. You can further save water by using the produced wastewater to wash your car, mop the floor, or do laundry.

This tankless RO water filtration system also prevents recontamination and saves 70% of under-sink space.

Its filters boast a twist-and-pull design that enables you to replace a filter in just 3 seconds without using any tools or moving the entire unit. In addition, its filter life indicators inform you when it’s time to change the filters, making the unit even easier to maintain.

The Waterdrop WD-G2P600-W perfectly meets the water needs of large families and companies. It features an upgraded water circuit and improved product safety, further making it ideal for the entire family’s use.

The filter also comes with automatic water shut-off valves, so you don’t have to worry about any leakage issues. Thanks to its fully enclosed design, the WD-G2P600-W does not make any sound louder than 55dB.

However, the RO system needs an electrical outlet to operate, which means it doesn’t work during power outages. The manufacturer also does not recommend using this model for well water because of its complex composition.

Pros

  • Extremely compact design
  • Only 2 filters need replacement
  • High 600 GPD output reduces waiting time at the sink
  • Affordable and pocket-friendly
  • Impressive drain ratio helps save water
  • Eliminates contaminants bigger than 0.0001 μm
  • Quiet and effective operation
  • Clear instructions ensure quick and easy installation

Cons

  • It lacks a post-carbon filter
  • Requires electricity to operate

Tankless RO System Buying Guide

What are Tankless RO Systems – and How Do They Work?

best tankless reverse osmosis system

Tankless reverse osmosis systems, or direct flow reverse osmosis filter systems, are a novelty in the RO filtration field.

Units that come with a tank work with the ‘storage before consumption’ principle, which means that they filter tap water and store it in the tank before allowing you to consume it.

On the other hand, tankless models don’t store water. Instead, they filter tap water and immediately ready it for consumption. Aside from the lack of a storage tank, tankless RO water systems work pretty much the same way as traditional reverse osmosis systems.

The process involves pushing water through a fine RO membrane that eliminates most contaminants in your water, including large and small particles, like chlorine and THMs.

Tankless reverse osmosis systems also combine RO membranes with several other water filters to eliminate up to 99% of all chemicals, odors, sediment, and colors from tap water. This makes them highly versatile and enables them to filter water, no matter your local water source.

All RO systems rely on water pressure to push the water through the RO membrane and other filters present in your filter system. If the incoming water pressure is low and does not meet the requirements of your RO system, you’ll need to add a booster pump, regardless of whether you have a tankless or tanked reverse osmosis system.

Why Buy a Tankless Reverse Osmosis System (vs. A Tank)?

It’s important to know that tankless and traditional reverse osmosis systems have a different number of RO membranes. Regular units use only one RO membrane, but tankless RO systems use multiple membranes for more effective and efficient filtration.

You should definitely purchase a tankless reverse osmosis system over one with a tank if you live in a home with limited space. This is because tankless models are half the size of traditional RO water filters and take up very little space.

If you store cleaning supplies under your kitchen sink, then you’ll appreciate the additional space as well!

Tankless reverse osmosis systems are also easier to install because almost everything is fitted into one case. This means there are fewer components and connections.

Tankless water filters are simpler to replace as well. You don’t have to shut off any water lines, use extra tools, or figure out any difficult access handles.  

One last advantage of tankless reverse osmosis systems is the prevention of secondary pollution from storage tanks. Although it is uncommon, storage tanks in normal RO water filtration systems can turn into a breeding ground for germs and bacteria that can contaminate the filtered drinking water.

But, since tankless systems don’t have storage tanks, you don’t have to worry about this problem!

What to Look for in a Tankless Reverse Osmosis System

best tankless reverse osmosis system

Tankless RO drinking water systems are a significant investment. To ensure you get the right fit and don’t end up wasting your money, we list and explain some important factors you should consider before finalizing your purchase:

Gallon Per Day

A unit’s GPD rating is, arguably, the most essential factor to consider when buying a tankless RO system. Make sure you check whether the unit meets your family’s drinking water needs.

While a higher GPD translates into better performance, purchasing a tankless RO water system with a higher GPD can be a waste of money if you have a small family.

Filtration Stages

It’s essential to consider the number of filters and the filtration stages. Most tankless reverse osmosis systems use filter composition technology to eliminate the contaminants in your tap water, but the unit’s filtration stages can affect the quality of filtered water.

Tankless reverse osmosis systems usually have 3-5 filtration stages. However, some units incorporate additional stages for ultra-safe drinking water.

Efficiency

Tankless RO water systems waste water during filtration, and their efficiency is measured by comparing the wasted water to the filtered water and is indicated by the drain ratio. Make sure you check the drain ratio and choose a model that is both cost-effective and eco-friendly.

Ease of Installation

If you’re somewhat handy and mechanical, you’ll find installing a tankless reverse osmosis system to be a piece of cake. However, it’s still better to choose a model that comes with a well-labeled diagram and simple, clear installation instructions.

Water Pressure

Since all RO systems use water pressure to remove contaminants from tap water, it’s vital to know a unit’s minimum pressure requirements and check it against your building’s minimum water supply pressure before purchasing it.

If you get low water pressure, we recommend attaching a booster pump for more effective filtration.

Water Source

It’s important to know whether your water comes from a city supply or a well. This will help you determine which tankless water purifier will best eliminate the contaminants and toxins in your water.

You can also determine which contaminants are in your water by conducting a water test with a certified lab.

Water Remineralization

Along with the toxins and contaminants, a tankless RO system might also remove a good number of healthy minerals from your tap water. In that case, it’s better to go for a tankless reverse osmosis system with remineralization to add them back.

Water remineralization is usually the last step in the filtration process before the water leaves the faucet.

Pros and Cons of Tankless RO Systems

best tankless reverse osmosis system

If you’re still unsure about purchasing a tankless RO system, you can compare the advantages and disadvantages before making a purchase.

In our opinion, the benefits definitely outweigh the drawbacks, but make sure you go through this section and decide for yourself!

Pros

Along with taking up less space, other advantages of a tankless RO system include:

  • Multiple membranes efficiently and effectively filter water
  • Filters and delivers water instantly, eliminating the need for waiting for water to collect in the RO tank
  • Instantly filtered water tastes better than water collected in a tank
  • More economical, as it only filters water when needed
  • Space-saving design makes it perfect for small houses and apartments

Cons

While a tankless water filter system might look like the perfect option for RO filtration, there are a few disadvantages that you should consider, such as:

  • Tankless units are more expensive than traditional RO systems
  • RO membrane replacement costs of tankless models are higher than traditional systems because of the use of multiple membranes
  • Some tankless reverse osmosis systems have water waste issues

Cleaning and Maintaining Tankless RO Systems

best tankless reverse osmosis system

Tankless models are the easiest reverse osmosis water systems to install. You can simply install them by using a power drill and some plumber’s tape. You just need to connect your RO unit to your pipes and install the faucet, and you’re ready to go!

On the other hand, larger RO systems require lots of drilling, tubing, and extra mounts for installation, making them more difficult and time-consuming to set up.

Tankless RO drinking water systems are also easier to use and maintain than other models. Most tankless units come with a cover that you just need to remove or flip up to gain access to the filters.

Replacing their filters is easy as well, as you simply need to twist the old filters to unlock them and click the new ones into place.

Some tankless systems come with a smart faucet and an onboard display, further making them easier to maintain. The LCD display shows the filter life and informs you when it’s time to replace the filter.

Meanwhile, smart faucets keep track of water quality, so you can change your filters before your water starts tasting bad.


Frequently Asked Questions

Do tankless reverse osmosis systems need electricity?

Since tankless reverse osmosis systems rely on water pressure, they don’t need electricity. You’ll only need electricity if it uses an ultraviolet lamp or an electric pressure-boost pump. Models with smart features like LED bulbs and TDS meters also require electricity.

Do tankless RO systems need additional maintenance?

Tankless RO systems rarely need any maintenance after installation. You’ll just need to replace the filters after every few months. Post- and pre-filters usually need replacement every 6 to 12 months, while reverse osmosis filters need replacement 1-5 years after installation.

Replacing filters in a tankless RO system is easy as well. You just need to twist and unlock the old filter to remove it and then secure the new one into place.

Are tankless reverse osmosis systems expensive?

Tankless RO systems are a bit more expensive and can cost anywhere from $300 to $600. This is because the system filters water instantly, giving you immediate access to clean drinking water. On the other hand, cheaper, tank-based models take several hours to top the storage tank with clean, purified water.


Final Verdict: What is the best tankless RO system sold today?

If you want a tankless RO system that is reliable, affordable, and will last a long time, then take a look at the Waterdrop WD-G3-W RO Filtration System.

If you need to support a larger family, then the Frizzlife PD600-TAM3 is the way to go.

And if you’re looking for something that doesn’t require a lot of maintenance, the Waterdrop WD-G2P600-W is a great choice.