Here we provide a detailed comparison of the best tankless reverse osmosis systems to complement our standard reverse osmosis system reviews.
Tankless reverse osmosis water filtrations systems have unique features and benefits that make them a very compelling option for filtering your drinking water at a single point of use (usually the kitchen sink).
We’ve setup all of these systems in our lab and can show you the top options based on our hand-on tests.
If you are looking for an innovative water filter system with the power of reverse osmosis, then a tankless RO system may be the right option.
Table of Contents
- Top Tankless RO Systems
- What is Reverse Osmosis?
- What is a Tankless System?
- Waterdrop G3 P800 Reverse Osmosis System
- NU Aqua Tankless 600 Reverse Osmosis System
- Frizzlife PD600-TAM3 with Alkaline Remineralization
- Waterdrop G3 P600 Reverse Osmosis System
- Compare the Top Tankless RO Systems
- You may also be interested in:
Top Tankless RO Systems
| Product | Top Features | Learn More or Buy |
|---|---|---|
 Waterdrop G3 P800 |
| 💲 💲 💲 |
 NU Aqua Tankless 600 GPD |
| 💲 💲 💲 |
 Frizzlife PD600-TAM3 |
| 💲 💲 💲 |
 Waterdrop G3 P600 |
| 💲 💲 💲 |
What is Reverse Osmosis?
Reverse osmosis water filtration (RO) is a process in which tap water is forced through a very fine membrane to remove contaminants.
Reverse osmosis water filtration systems combine an RO membrane with a series of other water filters to remove as much as 99% of all sediment, chemicals, colors, and odors from your tap water.
No one wants to worry about the environmental chemicals, boil water advisories, or old and dirty pipes. With a water filtration system, all of these issues can be cleaned up before you fill your glass.
You can learn much more about reverse osmosis water filtration and how it works on our reverse osmosis filter review page.
What is a Tankless System?
There are quite a few big differences between the tankless reverse osmosis systems in this review and “traditional” reverse osmosis systems that utilize a storage tank…
Tankless Throughput
Reverse osmosis water filtration systems with a storage tank deliver drinking water very quickly from a full pressurized tank. This is great for a single glass of water or if you want to connect the system to the water line of your ice maker.
Unfortunately, after you have drained the storage tank, the water pressure drops considerably and you have to wait for the system to slowly produce more filtered water.
The tankless reverse osmosis water filters on this page use an internal booster pump to filter water in real time at a high consistent rate. They also filter much higher gallons per day (GPD) than non-tankless systems.
Unfortunately, the booster pump does not provide immediate pressure and these systems don’t work well when connected to ice maker in your refrigerator.
Tankless Efficiency
The process of reverse osmosis water filtration “wastes” tap water by flushing a percentage of processed water containing all of the filtered contaminants down the drain.
Because of their internal booster pumps and high-throughput filters, tankless reverse osmosis drinking water systems are extremely efficient. The RO systems on this page produce between 1 and 2 gallons of filtered drinking water per 1 gallon of waste water.
Compare this to traditional RO systems that waste up to 4 gallons of tap water to produce one gallon of filtered water!
You also don’t have to worry about your tap water pressure when there is a booster pump to maintain optimum pressure.
Tankless System Size
A tankless reverse osmosis system is less than half the size of RO systems with a tank. If you store other things under your kitchen sink, then you will appreciate a slim and space-saving reverse osmosis unit.
Smart Features
Tankless water purification systems have many “smart” features that provide valuable information about your water and the status of the system.
All of these water filter systems have filter life indicators that remind you when it’s time to replace a filter. Efficient filters are critical to clean filtered water, so it is important to follow the manufacturer’s recommended schedule.
An extension of the filter indicators is a “smart faucet” that has an LED right built in. Undersink RO systems will have a dedicated water faucet for the filtered water. When the system is working normally, the LED will glow blue or green and if there is a problem, including the need to replace a filter, the LED will glow red.
TDS (total dissolved solids) is a measure of how much non-water (including contaminants) there are in your water. Some of these systems include a TDS meter that continuously tests your water and reports on the level of your filtered water. TDS level is an important indicator of water quality.
All of these smart features are possible because tankless revers osmosis water filters require a 110V power connection, which most traditional water filters don’t have.
Easy Installation and Maintenance
Tankless drinking water filtration systems are easier to install under your sink because almost everything is contained in one case. There are fewer connections and less components.
Also, tankless water filters are super simple to replace without shutting off any water lines, using extra tools, or difficult access angles.
All of our recommend tankless reverse osmosis systems have easy twist and replace filters right in the front of the case and you can expect almost no water drips during the filter replacement process.
No Secondary Pollution
One last benefit is the prevention of secondary pollution from the storage tank.
While uncommon, the storage tank in other reverse osmosis water filtration systems can become a breeding ground for bacteria that will contaminate your filtered drinking water.
Tankless systems don’t have this problem!
You can read more about the differences between tank and tankless undersink water filters in our article on WQPMag.com.
Tankless RO vs Storage Tank RO Systems Comparison
Tankless RO | RO with Tank | |
|---|---|---|
| System Size | Small | Large |
| Speed and GPD | High to Very High | Low to Medium |
| Waste Water | Low to Medium | Medium to Very High |
| Booster Pump | Always | Rarely |
| Filter Life Indicators | Always | Never |
| "Smart" Features | Often | Rarely |
| Ease of Maintenance | Easy | Medium to Difficult |
| Powers ice maker well | No | Yes |
| Requires Power | Always | Sometimes |
Waterdrop G3 P800 Reverse Osmosis System
With the Waterdrop G3 P800, you’ll never have to worry about running out of clean drinking water again.
This tankless under-sink RO system produces 800 gallons per day (GPD) which is more than enough for your household and small businesses that require large amounts of filtered water every single day!
The smart faucet is the “smartest” of any system with a real-time TDS meter and filter life indicators.
It also comes equipped with an integrated UV filtration stage – making it an excellent choice for well water or any installation where aquatic microorganisms are a concern.
Read our full hands-on review of the Waterdrop G3 P800.
Waterdrop Pros
- 800 GPD output is the highest of any system
- 3:1 waste water ratio is the most efficient of any system
- Integrated UV filter destroys microorganisms
- Integrated TDS meter reports on the quality of water in real time
- Smart faucet alerts you to upcoming filter changes and TDS readings
Waterdrop Cons
- System price is higher that most others
Use code RS199 for $199 OFF the Waterdrop G3 P800!
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Save up to $500 on top-rated water filters!
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Save over $160 in replacement filters with the G3 Combo Kit!
Waterdrop offers the G3 P800 as a bundle with 6 replacement filters worth $240 for only $78 more.
NU Aqua Tankless 600 Reverse Osmosis System
The NU Aqua Tankless 600 RO water filter hits the sweet spot of excellent performance, nice features including a smart faucet, and an average price among the tankless reverse osmosis competition.
Read our full review of the NU Aqua Tankless 600.
NU Aqua Pros
- Smart faucet alerts you when the filters need changing
- Alkaline remineralization stage
- Excellent 2:1 ratio of filtered drinking water to waste water
- Shortest tankless reverse osmosis option that should fit under most sinks
- 600 GPD filtering is the fastest available
- 5 year warranty when registered online is longest of any tankless system
- 100% Risk-free 120-day Home Trial
NU Aqua Cons
- No integrated TDS meter
NU Aqua Sale!
Frizzlife PD600-TAM3 with Alkaline Remineralization
The Frizzlife PD-600-TAM3 comes with an alkaline remineralization filter that adds essential minerals back to the filtered water and raises the pH to more than 7.5.
Read our full review of the Frizzlife PD600 water filtration system.
Frizzlife Pros
- Alkaline remineralization stage
- Real-time TDS readings on front of system
- Very good 1.5:1 ratio of filtered drinking water to waste water
- 600 GPD filtering is the fastest available
Frizzlife Cons
- No smart faucet but still has filter life indicators on system body
Waterdrop G3 P600 Reverse Osmosis System
The Waterdrop G3 is a powerful undersink reverse osmosis drinking water system that provides the most smart features of any tankless RO system.
It is also the only NSF-certified system in our roundup.
Read our full review of the Waterdrop G3 water purification system.
Waterdrop G3 Pros
- The only NSF/ANSI 58 certified tankless reverse osmosis system
- Smart faucet alerts you when the filters need changing and shows TDS readings
- Real-time TDS readings on front of system
- 7 stages of filtration
- Integrated leak detector in system body
Waterdrop G3 Cons
- Higher price than some of the competition
Use code RSG3 for $50 OFF the Waterdrop G3!
Waterdrop Labor Day Sale!
Save up to $500 on top-rated water filters!
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Compare the Top Tankless RO Systems
You may also be interested in:
Our recommended accessories for this or any other RO water system will help you customize your installation!
Compare these tankless drinking water systems with all other undersink reverse osmosis systems in our roundup review and guide.
If you like the idea of a tankless reverse osmosis machine and want even more installation flexibility, check our our reviews of countertop water filtration systems.
