Traditional under-sink Reverse osmosis treats water very slowly. For you to have an unlimited supply of filtered water, you are required to have a storage tank to store water as the system purifies. The tank helps store water so you never run out of filtered water. The new modern tankless reverse osmosis system works differently. It filters the water very fast, meaning you will get filtered water right away with no need for a storage tank.
Tankless RO system comparisons
| Name | Image | Features | Where to buy | |
|---|---|---|---|---|
| 1 | Frizzlife RO Reverse Osmosis Water Filtration System – PD600-TAM3 |   | 3stages filtration Replacement filters Alkaline remineralization Brushed nickel faucet 1.5: 1 drain ratio 600 GPD Smart LED Display | Buy now Frizzlife Buy now Amazon |
| 2 | Brondell Circle Reverse Osmosis System |   | 4-stage 400 GPD Fast Flow Faucet with LED filter change indicator 2:1 Drain Ratio | Buy now Amazon |
| 3 | Waterdrop G2 RO Reverse Osmosis Water Filtration System WD-G2-W |   | NSF Certified TDS Reduction 400 GPD Fast Flow Ordinary Faucet 1:1 Drain Ratio | Buy from Water drop filter Buy now Amazon |
| 4 | SimPure RO Reverse Osmosis Water Filtration System |   | 4stages filtration Replacement filters NSF certified Smart faucet 1.5: 1 drain ratio 400 GPD | Buy now Amazon |
| 5 | Frizzlife RO Reverse Osmosis Water Filtration System PD600 |   | 3stages filtration Replacement filters Brushed nickel faucet 1.5: 1 drain ratio 600 GPD Smart LED Display | Buy now Frizzlife Buy now Amazon |
| 6 | Oasis osmosis home RO Reverse Osmosis Water Filtration System |   | 3stages filtration Replacement filters Faucet 1.5: 1 drain ratio 600 GPD | Buy now Amazon |
| 7 | iSpring RO500 Tankless RO Reverse Osmosis Water Filtration System |   | Twist and Lock Filters Smart TDS Monitoring Faucet 500 GPD flow rate 3stages filtration Replacement filters 2: 1 drain ratio 600 GPD | Buy now Amazon |
| 8 | GreatWell ROG400 Tankless Reverse Osmosis Water Filtration System |   | Twist and Lock Filters RO Faucet 400 GPD flow rate 3stages filtration Replacement filters 1.5: 1 drain ratio Built-in true filter change indicator | Buy now Amazon |
| 9 | KFLOW Reverse Osmosis Water Filtration System |   | 5 stages filtration Replacement filters RO faucet 2: 1 drain ratio 400 GPD Smart LED Display | Buy now Amazon |
| 10 | Brio Reverse Osmosis Water Filtration System |   | 00 GPD Fast Flow 2:1 Pure to Drain - TDS Meter Smart Faucet Filter life indicator Provide two types of water filtered and purified 5 filter combined in two cartridges (sediment filter, GAC filter, RO membrane, carbon filter, sediment filter) | Buy now Amazon |
How tankless reverse osmosis system works
Compared to the traditional under-sink RO system, the new modern tankless reverse osmosis system requires no tank to store water because you will get water on demand within seconds.
The system comes with a housing that holds the filters and an RO faucet.
The filters are installed inside the reservoir or housing. The reservoir has a sleek, compact design that can be placed anywhere under your sink, taking up little space.
The faucet is installed into the hole on the countertop. If your sink or countertop does not have an existing hole you are required to drill.
This is a system perfect for someone who has a small space in places like the kitchen, bedroom, office, lobby, restaurant, and outdoor RV.
Advantages of a tankless reverse osmosis system
- The compact design takes less space in your home.
- You don’t have to wait long to get filtered water. Plugin the system into the power supply and get purified water right away.
- No plumbing or installation is required.
- Filter replacement is faster. Most systems adopt a twist-in design and can be replaced directly by one single turn. The design allows you to remove and replace the filter and RO membrane in as little as 3 seconds without moving the system or using any tools.
- Using no tank means the elimination of secondary pollution.
Cons
- It requires electricity to operate compared to the traditional reverse osmosis system that does not use electricity.
10 Best Tankless reverse osmosis system in 2022
- Faucet with LED filter change indicator: Brondell Circle Reverse Osmosis System
- Waterdrop G2 RO Reverse Osmosis Water Filtration System WD-G2-W
- Best with smart faucet: SimPure RO Reverse Osmosis Water Filtration System
- Best with Smart LED Display: Frizzlife RO Reverse Osmosis Water Filtration System PD600
- Best with filter indicator light: Oasis osmosis home RO Reverse Osmosis Water Filtration System
- Best with smart faucet: iSpring RO500 Tankless RO Reverse Osmosis Water Filtration System
- Best with Built-in true filter change indicator: GreatWell ROG400 Tankless Reverse Osmosis Water Filtration System
- Best with smart LED display panel: KFLOW Reverse Osmosis Water Filtration System
- Best with demineralization: Frizzlife RO Reverse Osmosis Water Filtration System – PD600-TAM3
- Best with smart faucet: Brio Reverse Osmosis Water Filtration System
- Best with UV: Waterdrop Countertop Reverse Osmosis Water Filtration System (WD-N1)
Tankless reverse osmosis system reviews
Brondell Circle Reverse Osmosis System
Features
- 4-stage
- 400 GPD Fast Flow
- Faucet with LED filter change indicator
- 2:1 Drain Ratio
Brondell Circle Reverse Osmosis System is a compact design where the reservoir and water filters are contained in a sleek case taking up less space under your sink.
This system is a 4-stage filtration system that includes filters such as
- Sediment filter
- Pre-carbon plus filter
- RO membrane filter
- Post carbon block filter
All the above filters help eliminate bad tastes, odors, heavy metals, pesticides, herbicides, fluoride, lead, radium, and many more chemicals from your water.
It features an integrated LED filter change indicator that conveniently reminds you when to replace your filters.
The Brondell Circle Reverse Osmosis Water Filtration Systemic Gold Seal-certified by the Water Quality Association for trusted performance and is certified for NSF/ANSI standards 42, 53, 58, and 372
The pure water to wastewater ratio is 2:1.
Installation video
Waterdrop Tankless reverse osmosis system
Buy here
Waterdrop WD-G3-W features
- NSF Certified
- TDS Reduction
- 400 GPD Fast Flow
- Ordinary Faucet
- 1:1 Drain Ratio
Waterdrop WD-G2-W is a tankless design reverse osmosis system that helps save more under sink storage space.
The system includes two filters:
- CF filters have a sediment PP membrane and an activated carbon block. It removes sediment, rust, large particles, colloids, chlorine, fluoride, and scale. The filter lasts for 12 months.
- The MRO filter has a sediment filter, a reverse osmosis membrane, and an activated carbon block. It helps reduce TDS and heavy metals. The filter lasts 24 months.
The Waterdrop RO system always has a stable water flow. It offers a fast water flow rate of up to 400 GPD and gets a cup of filtered water in about 12 seconds.
This model is available in two colors white and black
A replacement filter for a water drop
- Waterdrop WD-G2CF Filter, 12-month Lifetime, Replacement for WD-G2-B, WD-G2-W, WD-G2P600-W Reverse Osmosis System
- Waterdrop WD-G2MRO Filter, 2-year Lifetime, Replacement for WD-G2-B, WD-G2-W Reverse Osmosis System
Waterdrop RO Reverse Osmosis Drinking Water Filtration System WD-G3-W
Waterdrop WD-G3-W features
- NSF Certified
- TDS Reduction
- 400 GPD Fast Flow
- Smart Faucet
- 1:1 Drain Ratio
This model includes 3 filters in one and provides 7-stage of filtration that includes
- First Sediment PP membrane
- Carbon block filter
- Second Sediment PP membrane
- 3xlayers of RO membrane
- Post-activated carbon block layers
Waterdrop WD-G3-W replacement filter
- Waterdrop WD-G3-N3CB Filter, 1-year Lifetime, Replacement for WD-G3-W Reverse Osmosis System
- Waterdrop WD-G3-N2RO Filter, 2-year Lifetime, Replacement for WD-G3-W Reverse Osmosis System
How to install Waterdrop RO Reverse Osmosis Systems?
Waterdrop Reverse Osmosis System WD-D6-B
Waterdrop WD-D6-B features
- NSF Certified
- TDS Reduction
- 600 GPD Fast Flow
- Smart Faucet
- 1.5:1 Drain Ratio
Waterdrop WD-D6-B
Waterdrop Tankless reverse osmosis system comparisons.
| G2 RO WD-G2-W | WD-G3-W | WD-G2P600-W | WD-G2MNR-W (remineralization) | |
|---|---|---|---|---|
| Image | |   |   |   |
| Flow rate | 400GDP | 400GDP | 600GDP | 400GDP |
| Pure to drain rate | 1:1 | 1:1 | 2:1 | 1:1 |
| Faucet | ordinary | Smart faucet | ordinary | ordinary |
| Display | Filter life span | Filter life span & TDS | Filter life span | Filter life span |
| Replacement filter | CF MRO | CF RO CB | RO CF | Remineralization CF RO |
| BUY here | Water drop filter | Water drop | Water drop filter | Water drop |
| Dimensions | 17.32*5.91*13.9 | 18.06*5.68*17.76 | 17.32*5.91*13.9 | 17.32*5.91*13.9 |
Features
- 4stages filtration
- Replacement filters
- NSF certified
- Smart faucet
- 1.5: 1 drain ratio
- 400 GPD
SimPure Q6 uses 4 filtration stages to remove contaminants such as lead, chlorine, fluoride, chloramine, odors, heavy metals, chemicals, and limescale.
The 4 stages include:
- Stage 1: Sediment PP membrane – removes dirt, dust, rust, sand, and sediment.
- Stage 2: Active carbon block-remove chlorine, fluoride, and lead.
- Stage 3: Sediment PP membrane removes particles, limescale, and nematodes.
- Stage 4: The reverse osmosis membrane filters out total dissolved solids (TDS), heavy metals, viruses, bacteria, and organic matter.
It comes with a filter that includes a composite filter (PP filter and carbon block filter) and a 0.0001 micron RO membrane.
To guarantee safety the system is NSF certified.
This system can produce 400 gallons of filtered water per day at a rate of 1300 ml per minute. The pure to drain water ratio is up to 1.5:1.
It features LED light on the faucet that indicates the system status; It will change to red when a filter requires changing.
When it comes to changing the filter, the Simpure Q6 features a unique twist-and-pull design of the system filter cartridges that allows you to remove and replace the PPC filter and RO membrane in as little as 3 seconds without moving the system or using any tools.
Replacement filter
- SimPure Q6 PPC Filter Replacement Cartridge 6-12 Months Replacement Cartridge(1 Pack)
- SimPure Q6 RO Filter Replacement Cartridge 12-24 Months Replacement Cartridge(1 Pack)
Features
- 3stages filtration
- Replacement filters
- Brushed nickel faucet
- 1.5: 1 drain ratio
- 600 GPD
- Smart LED Display
This is Frizzlife PD600 which utilizes a composite pre-filter and RO membrane.
The difference from Frizzlife PD600-TAM3 is the system is alkaline and PD600 is not alkaline.
This system of filtering water uses a 2-in-1 filter that filters water in two stages. The stages include
- Stage 1: Pleated 2-in-1 filter (ASR211) – blocks fine debris and reduces particles such as sand silt, rust, and insoluble impurities. It conditions the water and prolongs the service life of the RO membrane.
- Stage 2: High grade 0.0001 micron RO membrane (ASR212) – The new-tech membrane gets rid of 99.99% of 1000+ contaminants, including chlorine, lead, heavy metals, fluoride, VOCs, chloramine, et
It features a 1.5:1 pure-to-drain ratio and a smart LED display. The LED display tells Real-Time OUT TDS after filtration and the remaining lifespan of each filter.
It also features a built-in TDS checker that constantly monitors the quality of your drinking water 24/7. Acting as an intelligent reminder, the color-coded indicator will always keep you updated about filter usage and remind you to change filters in advance.
FRIZZLIFE Replacement Filter Cartridge Replacement filters
- FRIZZLIFE ASR211 Replacement Filter Cartridge for PD600, PD400, PD500 Reverse Osmosis System (1st Stage)
- FRIZZLIFE ASR212-600G RO Replacement Filter Cartridge for PD600 (2nd Stage)
Frizzlife PD600 Reverse Osmosis installation
This model is also available in a different capacity
Frizzlife Reverse Osmosis System PD400-Tankless 400 GPD Drinking Water Filtration System.
Frizzlife Reverse Osmosis Water Filtration System PD500- Tankless 500 GPD High Output RO filter.
Frizzlife PD400/PD500 Reverse Osmosis System Installation Guide
Features
- 3stages filtration
- Replacement filters
- Faucet
- 1.5: 1 drain ratio
- 600 GPD
Oasis osmosis home includes 3 filters in 2. The filter includes:
Activated Carbon Block Filter removes sediment, rust, large particles, chlorine, fluoride, and colloids.
Reverse Osmosis Membrane Composite Filter eliminates impurities like heavy metals, TDS, bacteria, and other harmful microorganisms.
Each package comes with two filters: a Ro membrane and a multi-layered composite filter that includes a PP cotton filter, activated carbon, and softening resin.
This system drain ratio is 1.5:1 and has a flow rate of 500 GPD.
The system will alert you when it’s time to replace the filters. The filter indicator light will start flashing red and the buzzer alarm will start.
OASIS OSMOSIS HOME Replacement filters
- OASIS OSMOSIS HOME RO Membrane Filter for 600GPD Reverse Osmosis System for Water Filtering
- OASIS OSMOSIS HOME RO Activated Carbon Filter for 600GPD Reverse Osmosis System for Water Filtering
- Twist and Lock Filters
- Smart TDS Monitoring Faucet
- 500 GPD flow rate
- 3stages filtration
- Replacement filters
- 2: 1 drain ratio
- 600 GPD
iSpring RO500 is a 3-stage water system. The three stages include:
- 1st Stage: 3-in-1 composite that utilizes multi-layer design. The layers include Sediment and Carbon Block filter that help remove sand, rust, dirt, and particles as well as chlorine and unpleasant odor.
- 2nd-stage: advanced RO Membrane that helps remove lead, fluoride, arsenic, asbestos,
- 3rd stage: Carbon Block Filter that further polishes purified water and bring you tasty and odorless water.
This system’s pure water to wastewater ratio is up to 2: 1.
It features a high-quality smart faucet that has a real-time indicator that displays the TDS of your filtered water, suggests a filter change schedule, and shows codes that help with troubleshooting.
RO500 membrane is rated at 500 gallons per day
iSpring RO500 Tankless RO Reverse Osmosis Water Filtration System Replacement Filter.
- iSpring FCF500 Composite Filter Replacement for RO500 Tankless Reverse Osmosis Water Filtration System
- iSpring MRO500 High Flow RO Membrane Replacement Filter for Tankless Reverse Osmosis Water Filtration System RO500, 500 GPD
- iSpring FCB500 Carbon Block Filter Replacement for RO500 Tankless Reverse Osmosis Water Filtration System
- iSpring F5-RO500 2-Year Filter Replacement Pack for RO500 Tankless Reverse Osmosis Water Filtration System-Includes 2 composite filters FCF500, 1 MRO500 RO membrane, and 2 coconut shell activated carbon blocks FCB500.
- iSpring F2-RO500 1-Year Replacement Filter Pack for the RO500 Tankless Reverse Osmosis Water Filtration System includes composite filters FCF500 and a coconut shell activated carbon block FCB500.
iSpring RO500 Tankless RO Reverse Osmosis 500GPD Water Filtration System DIY Installation
- Twist and Lock Filters
- RO Faucet
- 400 GPD flow rate
- 3stages filtration
- Replacement filters
- 1.5: 1 drain ratio
- Built-in true filter change indicator
GreatWell ROG400 membrane is rated at 400 GPD with a pure to wastewater ratio up to 1.5: 1.
This system filters water in three stages using the following filters
PAC composite filter: a 3-in-1 carbon wrap filter that works as a combination of two polypropylene sediment filters and a carbon filter. The filter helps remove sand, rust, chlorine, odor, and smell.
ROG400’s RO membrane is rated at 400GPD made by GE that helps remove lead, fluoride, arsenic, hormones, asbestos, and more for up to 3 years.
An activated carbon filter is used to further polish water to ensure better taste and odorless high-quality water.
The unit can be connected to the ice maker or refrigerator.
To guarantee the quality, the Greatwall components are tested by an independent 3rd party against NSF/ANSI standards.
It features a built-in true filter change indicator that monitors each filter’s life.
Greatwell Tankless Reverse Osmosis (RO) Water Filtration System replacement filter
- GREATWELL F2ROG400 High Capacity 6-Month Filter Set 400 GPD Tankless Reverse Osmosis (RO) Water Filtration System Stage 1 and 3
- GREAT WELL MRO400 High Capacity 400GPD RO Membrane Replacement 400 GPD Tankless Reverse Osmosis (RO) Water Filtration System – Stage 2
Features
- 5 stages filtration
- Replacement filters
- RO faucet
- 2: 1 drain ratio
- 400 GPD
- Smart LED Display
KFLOW is a 5-stage water filtration system that uses three filters. The filters include
- The PCP filter includes 2 sediment PP membranes and 1 activated carbon block, ideal for removing sediment, rust, particles, colloids, chlorine, fluoride, and scale.
- Reverse osmosis filter (0.0001-micron accuracy, helps remove chlorides, lead, heavy metals, mercury, chloramine, chromium, arsenic, and radium.
- The rear CF filter improves the taste and smell of water.
The KFLOW membrane is rated at 400 GPD and has a 2:1 drain ratio.
It features a smart filter life monitor that displays the remaining life of filter cartridges.
The pack includes an upgraded instruction manual, X6 reverse osmosis system, RO faucet, feed water adapter, 1/2”-3/8” converter set, 3/8” water tube, 1/4” water tube, drain saddle set, power adapter, and leakage buzzer.
KFLOW Replacement filters
- KFLOW 1st Stage Replacement Water Filter Cartridge for KFL-X6 (PCP Filter)
- KFLOW 2nd Stage Replacement Water Filter Cartridge for KFL-X6 (RO Membrane)
- KFLOW 3rd Stage Replacement Water Filter Cartridge for KFL-X6 (CF Filter)
Tankless reverse osmosis system with remineralization
- Frizzlife RO Reverse Osmosis Water Filtration System – PD600-TAM3
Features
- 3stages filtration
- Replacement filters
- Alkaline remineralization
- Brushed nickel faucet
- 1.5: 1 drain ratio
- 600 GPD
- Smart LED Display
Frizzlife PD600-TAM3 is an alkaline reverse osmosis system.
The reverse osmosis membrane removes natural minerals leaving you with acidic water. This system has a stage-3 filter that restores health-benefiting essential minerals to your water. It also balances the alkalinity of RO water and adjusts the PH to more than 7.5.
This system produces 600 gallons of water per day.
It features a smart display panel that tells real-time out TDS and the remaining lifespan of each filter
The pure to-drain water ratio is up to 1.5: 1.
This system filter water in three stages
- Filter 1：3-in-1 composite filter (ASR211) – Blocks fine debris and reduces particles such as sand, silt, rust, and insoluble impurities. This filter conditions the water and prolongs the service life of the RO membrane.
- Filter 2: High grade 0.0001 micron RO membrane (ASR212) – Gets rid of 99.99% of 1000+ contaminants, including chlorine, lead, heavy metals, fluoride, mercury, VOCs, chloramine, arsenic, and much more.
- Filter 3: Alkaline remineralization filter (TAM3) – Restores natural minerals, balances the alkalinity of RO water, and adjusts the PH to more than 7.5. Reduces bad taste, odor & polishes the flavor.
The package includes a brushed nickel faucet, system cover, tubing, wastewater clamp, fittings, screws, and 3 filters (pleated carbon compound filter, Ro membrane, and remineralization filter).
The system can be used for both 110v and 220v.
Frizzlife PD600-TAM3 tankless RO Reverse Osmosis Water Filtration System Replacement Filter Cartridge
- FRIZZLIFE ASR211 Replacement Filter Cartridge for PD600, PD400, PD500 Reverse Osmosis System (1st Stage)
- FRIZZLIFE ASR212-400G RO Replacement Filter Cartridge for PD400 (2nd Stage)
- Frizzlife Alkaline Remineralization Under Sink Water Filtration – 1/4” Quick Connect Post Filter for RO Reverse Osmosis Filter System, 3 Stages, Adjust PH, Restore Essential Minerals, TAM3
This system by water drop reduces harmful substances, and an extra mineral filter restores beneficial minerals.
It uses an RO membrane, two sediment PP membranes, two activated carbon blocks, and a PET pleated membrane to reduce contaminants as follows:
Sediment PP membrane x2: Reduces rust, sediment, suspended solids, and other large particles.
Premium activated carbon block x2: Reduces chlorine, organic matter, taste, and odor.
0.0001-micron high-grade reverse osmosis membrane: Reduces TDS, lead, salt, fluoride, nitrates, PFAS, etc.
PET pleated filter: Reduces large particles like powdered carbon.
The system comes with an external mineral water filter to add beneficial minerals like calcium, and magnesium.
With a fast& stable water flow of 400 GPD, you can fill a cup of water within 12 seconds.
This reverse osmosis remineralization system has a low drain ratio of 1:1.
It has an indicator used to remind you to replace filters on time.
The pack includes a plastic system cover, metal Faucet, RO filter: reverse osmosis membrane & carbon block & pp cotton, CF filter: pp cotton & carbon block, and Mineralization filter: natural mineral material
Replacement for water drop WD-G2MNR-W
This is sediment PP membrane and activated carbon that lasts for 12 months or 1100 gallons.
This is a reverse osmosis membrane and activated carbon that last for 24 months or 2200 gallons.
Waterdrop Remineralization Under Sink Water Filtration
This is a remineralization filter that lasts for 12 months or 1100 gallons.
Brio Reverse Osmosis Water Filtration System
- 700 GPD Fast Flow
- 2:1 Pure to Drain –
- TDS meter
- Smart Faucet
- Filter life indicator
- Provide two types of water: filtered and purified (for filtered, unfiltered water goes through a two-stage filter (does not go through RO membrane) to remove contaminants and purified goes through five filters).
- Five filters are combined into two cartridges (sediment filter, GAC filter, RO membrane, carbon filter, sediment filter).
- Replacement filter
Brio Quick Change 10″ Replacement Water Filter Cartridge (STAGE 1 – Sediment)
Brio 50 GPD Membrane RO Reverse Osmosis Water System Filter Replacement 2″ X 10″
Brio Quick Change 10″ Replacement Water Filter Cartridge (Stage 3 – Post Carbon)
5 Micron SEDIMENT PP Water Filter – Reverse Osmosis Replacement Filter 2.5″x10″
After purchasing your RO system, make sure you find a TDS meter /water tester to see whether the system is working well.
Tankless reverse osmosis system with UV light
Waterdrop Countertop Reverse Osmosis Water Filtration System (WD-N1)
Features
- UV light works for 60,000 hours continuously.
- 3:1 pure to drain ratio
- The 4-stage water filter includes the UV light, CF filter (including coconut carbon block and PP cotton), and MRO filter, which can last up to 6 and 18 months, respectively.
- A smart panel displays Total-Dissolved Solids (TDS), filter life indicators, volume settings, water shortage alerts, and an auto-flush mode.
How to install Water drop N1 Countertop Reverse Osmosis System
Tankless reverse osmosis system Canada
Waterdrop RO Reverse Osmosis Water Filtration System, 600 GPD WD-G2P600-W, 2:1 Pure to Drain, the smart panel.
Waterdrop RO Reverse Osmosis Drinking Water Filtration System, NSF Certified, TDS Reduction, 400 GPD WD-G3-W, 1:1 Drain Ratio, smart faucet.
Waterdrop RO Reverse Osmosis Water Filtration System, TDS Reduction, 400 GPD, WD-G2-B (black)
iSpring RO500 Tankless RO Reverse Osmosis Water Filtration System
Frizzlife Reverse Osmosis Water Filtration System – Countertop RO Water Filter, 4 Stage,
GREATWELL ROG400 Tankless Reverse Osmosis (RO)
KFLOW Reverse Osmosis Water Filtration System, Tankless, 400GPD, 2:1 Drain Ratio, (KFL-X6)
To select the replacement filter for your system, see our post about the reverse osmosis replacement filter.
After purchasing your RO system, make sure you find a TDS meter /water test strip. Both the test strip and the TDS meter will help test filtered water from your RO system to confirm whether the system is working well.
Are tankless reverse osmosis systems worth it?
Yes! Tankless RO systems are worth it. If you want a system that helps save your under-sink space, less hustle installation, and filter change this is a system worth your investment.
How much is a tankless RO system?
Tankless RO system price depends on the brand. Some are fair and others are expensive depending on the filter included in the system
