best tankless reverse osmosis system

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Ensuring clean drinking water can be tricky. Regular water systems can have undetected molecules, causing major health issues. However, to address this, you can install a tankless reverse osmosis system to clean your water effectively.

A reverse osmosis system is a water-purifying process that can remove smaller particles and minerals. It allows water to undergo a series of filtration stages to create purified drinking water by applying high pressure to separate molecules and filtered water.

Here, I’ll guide you to my take on the best tankless reverse osmosis systems that provide quality filtering of your water using an RO filter.

What is the best tankless reverse osmosis system?

Here are some top-notch tankless reverse osmosis systems that can catch your eye.

  1. NU Aqua Efficiency Series: Best overall pick
  2. Waterdrop G3P800: Best for buyers with a flexible budget looking for easy-to-use options without risking quality.
  3. Frizzlife PD600-TAM3: Best for buyers looking for efficient Tankless RO system filtering and remineralized water in one
  4. iSpring 500 GPD: Best for buyers looking for an affordable tankless reverse osmosis system that does the job at an impressive rate.
  5. Waterdrop G3: Best for buyers looking for an affordable alternative to the Waterdrop G3P800 that provides the same great filtration quality.

1. NU Aqua

Top Pick

NU Aqua Efficiency Series

My personal choice for the best tankless reverse osmosis system is the NU Aqua efficiency tankless RO system which provides activated carbon block filter and remineralized water at a budget-friendly price.

You won’t need to buy a separate alkalizing system as it already remineralizes my water for drinking. It also provides smart LED notifiers that tell you when to change filters.

My Take: The NU aqua efficiency series is a 4-stage filtration compact-sized RO system that effectively cancels out dangerous bacteria and also provides remineralization. It offers a less-stress experience for buyers by having an easy installation process and filter changes.

Best for: Buyers with a flexible budget looking for easy-to-use options without risking quality.

Key Features:

  • 4-Stage Filtration
    • A 2-stage filter of polypropylene & carbon block filter
    • Granulated Activated Carbon filter (GAC) – lasts for 1 year
    • 600 gpd RO membrane – Lives up to 36 months
  • Efficiency Ratio: 2:1
  • Flow rate: 600 gallons per day
  • Integrated booster internal pump
  • Length: 18.12 inches
  • Width: 5.67 inches
  • Height: 17.72 inches


The NU Aqua Efficiency Series costs $471.96 and comes with additional benefits:

  • 5-year warranty (Free)
  • Currently on Summer Sale 20% Off Discount
  • Free shipping across
  • 120-day money-back guarantee

Likes/Dislikes about NU Aqua Efficiency Series


  • Remineralization – Does not cancel out healthy minerals.
  • No extra tools are needed – Has an easy twist and pull switch when replacing filters.
  • Fast flow rate – Can produce 600 gallons of water per day.
  • Good filtration – Has a 4-stage filtration that reduces specific contaminants while remineralizing water, highly competitive against traditional RO systems.
  • Clear filter life – The Reverse Osmosis membrane lasts around 36 months.
  • Easiest to use – Smallest tankless reverse osmosis system and easy to change filters. Equipped with light indicators that notify you when it’s time to replace filters and current water quality.
  • UV light – Optional UV filter using UV light


  • No certification – Is not approved by additional certifications from institutions but personal reviews.
  • Produces less pressure – This can cause the production rate of filtered water to be slower.
  • Short wire cord – It is not recommended to be a whole house RO system. The faucet cord is only long enough for under-the-sink installations.

Overall User Experience

The NU Aqua Efficiency Series Tankless 600GPD is an efficient rankless RO system that provides quality, clean mineral water through carbon filters. But, it can take more time as filling a gallon jug of water takes up to 3 1/2 minutes.

Overall, the water produced tastes fresh, which I highly recommend. It provides quality carbon filtration with convenience.

2. Waterdrop G3P800

Runner up

Waterdrop G3P800

The WaterG3P800 is a state-of-the-art smart faucet RO system that provides quality UV sterilization for thorough disinfecting and filtration for cleaning water.

My Take: It’s currently the best efficiency ratio Tankless RO system with its 3-stage filters and 9-layer membrane for removing smaller molecules like heavy metals, chlorine, and bacteria. 

Best for: Families and businesses who are looking for the best tankless reverse osmosis system money can offer.

Key Features:

  • 3-Stage Filtration
  • Efficiency Ratio: 3.1
  • 50-year UV sterilization
  • Certification: Federal Communications Commission, NSF/ANSI standard, EU Standards, and UKCA, German Red Dot Design Awards 2019
  • Flow rate: 800 gallons per day
  • The 9th Filtration layer serves as a scale inhibitor to block water scales
  • Water to feed: Municipal Tap Water (Refrain from feeding well water)
  • Length: 18.12 inches
  • Width: 5.67 inches
  • Height: 17.72 inches


The Water Drop G3P800 costs $999.00 but can also be paid through installments through the following applications:

  • Klarna – Pay as low as $167.00 a month
  • Afterpay – Pay $249.00 in 4 interest-free installments.

Likes/Dislikes about Waterdrop G3P800


  • Intelligence – Contains smart faucet functions that notify you of filter life indicators, TDS indicators, and malfunctions. A filter life indicator is such a nice feature to have.
  • Quality Purified Water – Has an efficiency ratio of 3:1 pure water to waste water despite an in-depth filtration process.
  • Quick – Can produce 800 gallons of water daily, perfect for families.
  • Great filtration – The G3P800 provides nine layers of reverse osmosis membrane filter that effectively separate water from various particles, which surpasses traditional RO systems.
  • Bacteria Killer – Is equipped with a UV sterilizer to kill the smallest contaminants, such as bacteria and viruses.
  • Sustainable – Saves energy with its low drain ratio.
  • Easy to use – Structured to have removable filters from the front to avoid additional maintenance and complications in placing it.
  • Spacious – Sleek unit that can comfortably fit your kitchen sink.


  • Costly – Purchasing the G3P800 requires a high budget with its $999 overall price. But you can apply for down payment settlements or monthly installations.
  • Not Mineralized – An RO system traps bacteria and other dangerous contaminants and eliminates minerals. You must purchase a separate alkaline remineralization filter for mineral water.

Overall User Experience

The Waterdrop G3P800 is a user-friendly smart faucet packed with advanced options to provide clean, purified water. Its intelligence features light color notifiers that let you know whether there are life indicator detectors, malfunctions, or TDS indicators in your system. Additionally, the filter cartridge is easily accessible from the front for changing when it is time for replacement filter s.

Overall, may seem costly but offers long-term benefits for users who are looking for a beyond effective filtration RO system that can successfully eliminate harmful bacteria while saving water.

3. Frizzlife PD600-TAM3


Frizzlife PD600-TAM3

The Frizzlife tankless RO system provides remineralized and alkalized purified water at a more affordable price.

My Take: It also offers a TDS system that monitors your drinking water quality 24/7. Frizzlife also provides a faucet when purchased and works at an efficient 600 gallons per day.

Best for: Buyers looking for efficient Tankless RO system filtering and remineralized water in one.

Key Features:

  • 7-stage filtration system
  • Efficiency Ratio: 1:5:1
  • Flow rate: 600 gallons per day
  • alkaline filter
  • TDS system
  • Length: 14.7 inches
  • Width: 5.3 inches
  • Height: 15.5 inches


The Frizzlife PD600-TAM3 costs overall $469.99 and is generous with discounts:

  • $80 off – Use RO80OFF at checkout

Likes/Dislikes about Frizzlife pd600-tam3


  • Good Remineralization – Produces high-quality mineral drinking water, it restores healthy minerals.
  • Sustainable – Saves energy up to 450% compared to traditional tankless RO systems with its efficiency ratio.
  • Good filtration – Contains an 8-layer filtration system that eliminates specific odors, microorganic contaminants like Cyst, pollutants, and heavy metals while it carbon filters your water before remineralization.


  • Hard installation – Installing may be challenging as it requires 100-volt power to a PD-600. It can also take up to an hour or longer for those who need to refurbish wires and sockets. May also require additional tools like Teflon tape.
  • Leak Issues – Possible leaking when installing, you will need to contact Frizzlife for assistance.
  • Slow – Fills half a gallon of water within 2-3 minutes.
  • Noisy – Produces a humming sound from the motor which can feel concerning for users.

Overall User Experience

The Frizzlife tankless RO system pd600-tam3 can be hard to install but offers quality mineralized water at the comfort of Smart LED color indicators that notify you in advance to change filters to avoid last-minute changes.

It provides in-depth filtration from heavy metals, odors, and contaminants to protect you from illnesses while making purified mineral water.

4. iSpring 500 GPD

Efficient System

iSpring 500 GPD

The iSpring 500 GPD is an efficient and easy-to-use RO system that provides a TDS meter to assure you quality filtered water.

My Take: It also has a reinforced integrated water route for easier installation and prevents water waste.

Best for: Buyers looking for an affordable tankless reverse osmosis system that does the job at an impressive rate.

Key Features:

  • 6-stage filtration system
  • Low Drain Ratio: 2:1
  • Flow rate: 500 gallons per day
  • TDS meter
  • Length: 19 inches
  • Width: 8 inches
  • Height: 24 inches


The iSpring 500 GPD costs $564.00 overall, but you can also avail of a 12-month installment:

  • $48.00 Monthly installment Option

Likes/Dislikes about iSPRING 500 GPD


  • Efficient filtration – The 8-stage filtration provides an in-depth cleaning to ensure your water is safe from contaminants and heavy metals.
  • Sustainable – Saves up to 400% of water compared to traditional RO systems.
  • Budget Friendly – Has the most affordable installment option.
  • Easy installation – The iSpring 500 GPD grants you less stress when installing.
  • Sleek Design – Has an appealing smart faucet design.
  • Quiet – Does not produce a “humming” sound when using.


  • Large – Currently the largest model among its competitors.
  • Lesser smart faucet functions – The iSpring 500 GPD provides fewer smart LED notifiers.
  • Not remineralized – You’ll need to buy an additional remineralization filter.
  • No additional certification – Is not backed up by special institutions for certification.

Overall User Experience

The Waterdrop G3 serves as a budget-friendly alternative. It may not have the more advanced properties of its competitors but it has more filtration stages that greatly reduce the harmful contaminants and uses more natural ingredients.

5. Waterdrop G3

8 Stage filtration system

Waterdrop G3

The Waterdrop G3 is a mother version of the WaterdropG3P800 that provides quality filtration without UV sterilization.

My Take: It provides an 8-stage filtration system that effectively reduces TDS, heavy metals, PFAs, salts, radium nitrate, etc.

Best for: Looking for an affordable alternative for the Waterdrop G3P800 that provides the same great filtration quality.

Key Features:

  • 8-stage filtration system
  • Low Drain Ratio: 1:1
  • Flow rate: 400 gallons per day
  • Certification: NFS 372 and a third-party laboratory, certified against NSF 372
  • TDS indicator system
  • Length: 18.12 inches
  • Width: 5.67 inches
  • Height: 17.72 inches


The Waterdrop G3 costs an overall $539 but can be paid in installments through the following applications:

  • Klarna – 4 interest-free installments of $134.75
  • Free shipping
  • 30-day money back
  • Afterpay – Also offers 4 interest-free installments of $134.75

Likes/Dislikes about Waterdrop G3


  • Efficient filtration – The 8-stage filtration provides an in-depth cleaning to ensure your water is clear of contaminants and heavy metals.
  • Budget Friendly – More affordable compared to other tankless reverse osmosis systems
  • Certified – Tested by a third-party laboratory and NSF certified for approval.
  • Appealing – Has an attractive, sleek build with a high-quality smart faucet provided.


  • Allergy risk – The carbon block filter is made from natural coconut shells, you will need to confirm whether or not you are allergic to it.
  • Less smart faucet functions – This does not notify you when to change the filters and other light color indicators.
  • Slower model – Much slower than the 600-800 gallons per day of water production. Takes a bit more time to fill gallons.
  • Not mineralized – You will need to purchase a separate remineralization filter.

Overall User Experience

The Waterdrop G3 serves as a budget-friendly alternative. It may not have the more advanced properties of its competitors, but it has more filtration stages that significantly reduce harmful contaminants and uses more natural ingredients.

Now that you know my top picks for an ideal Tankless RO system for your household, knowing how it works and why it’s important for your household is another factor to consider before buying.

To help you, here is a comprehensive guide to knowing what a Tankless RO system should do and why my chosen tankless RO systems are the best there are.

What is a Reverse Osmosis?

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Reverse Osmosis is the process of applying pressure to water in the opposite direction of an Osmosis System where water passes through a semipermeable membrane called the reverse osmosis membrane that allows only a microscopic and filtered amount of molecules to pass and become a dilute or purified solution.

Reverse Osmosis Systems are one of the most effective processes to filter water by adding extra water pressure in the opposite direction to the osmosis system. Homes today aim to install this filtration system to guarantee your water is free from water-borne diseases that traditional filtration systems don’t eliminate.

Osmosis system vs. Reverse Osmosis system

The Osmosis system is a natural process of water and molecules passing through a membrane where a weaker solution is overpowered and absorbed by a strong saline solution. It occurs in natural occurrences such as plant roots absorbing water from the soil.

On the other hand, the RO system is an artificial process that blocks the passage of micro-particles aside from water. The system adds extra pressure to push the water flow through the reverse osmosis membrane to create more concentrated pure water that is separated from contaminants.

Essentially, the RO system’s water flows in one direction towards a purified solution that travels through the RO membrane. Though both Osmosis and Reverse Osmosis block the passage of particles like ions, bacteria, sodium, and other contaminants, the RO system applies great pressure to force only smaller and ionized molecules to pass the membrane into filtered water.

Why do you need a reverse osmosis system?

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An RO water filter has a passage size of approximately 0.0001 microns for clean water, implying that the amount of particles allowed to pass this type of filtering is smaller and stricter. Reverse Osmosis can exterminate even the most specific contaminants from water that other systems can overlook. 

The RO system is highly effective in removing particles like bacteria, protozoa (single-celled organisms), viruses, and common chemicals such as metal ions, sodium, chloride, calcium, etc.

Having particles dissolved in the RO water filtration system can avert you from diseases. Drinking water containing protozoa can lead to conditions such as Giardia, Malaria, and Toxoplasmosis. On the other hand, drinking water with traces of viruses and bacteria can lead to several deadly infections and diseases.

For a quick basis, here’s a guide to what particles are being extracted by Reverse Osmosis systems and what diseases you prevent by using it to purify your water:

How does a tankless reverse osmosis work?

Unlike its counterpart’s natural water flow, the RO system aims to produce purified water stripped from specific particles.

Reverse Osmosis systems use high pressure to push water across the semi-permeable membrane to separate approximately 99% of contaminants from the solution. The water undergoes a steady process that ensures it is demineralized and deionized from lingering chemicals or dissolved solids:

  1. Feed water is pumped into the tankless RO system and transported to the filters.
  2. The Filters, such as the carbon block layer, will dissolve 95%-99% of salts, odors, and chlorine. It will also remove contaminants and other bacteria. This process may depend on how many filter stages your Tankless RO system has.
  3. After filtering, it will move to the membrane for separation from cleaned water.
  4. The Tankless RO system will drain the wastewater containing the total dissolved solids, viruses, protozoa, and other particles separated from the purified water.
  5. Filtered water will flow out of the faucet connected to the system.

Where can you use a Reverse Osmosis System?

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There are spots in your home where using a reverse osmosis system is best. For tankless systems, here are the answers to where you can place your Tankless RO system:

Under the sink

Tankless RO systems are frequently built to be perfectly placed under the sink to connect the wires and drainage along with the plug for the electricity.

Whole house RO system

A Tankless RO system’s cord and proficiency rate is equipped to be connected to your entire home. This would require you to buy an expensive Tankless Reverse Osmosis filter.


You can connect your under-sink Tankless reverse osmosis outlets to your refrigerator to produce clean, better-quality ice water.

What are the Benefits of an RO System?

Tankless Reverse osmosis systems give you quality filtration with comfort and are guaranteed to disinfect Here are some of its best features to keep in mind:

Efficient Cleaning

Built to specially combat micro-sized particles and bacteria that a regular Osmosis System overlooks.


Saves space and energy while providing quality purified water, unlike a storage tank that often fills under your sink and only has a 1:1 pure to waste ratio.

Advanced Technology

These can offer the best user experience with smart faucet health indicators to notify you when you should change your filters rather than waiting for them to turn brown. Other advanced RO systems provide sterilization and activated carbon block layers.


Tankless RO systems are the peak of water flow rates by providing up to 800 gallons per day of purified water supply. It can fill a cup for 6 seconds.

What are the Disadvantages of an RO System?

Despite its impressive performance rate and spacious build, there are still a few cons of Tankless RO systems you should consider:


You will need a hefty budget to choose the perfect tankless reverse osmosis without compromising any preferences.

Not expansive

The wire cords may not be long enough to install in other rooms or units.

Needs electricity

Using a tankless RO system will require electricity for the smart LED features.

“TDS Creep”

Tankless systems can have a tendency to provide unfiltered water or water with higher TDS than tap during the first few seconds before pouring filtered water.

Does not mineralize water

Reverse Osmosis systems also filter out beneficial minerals and calcium. However, a few Tankless RO systems, like my pick, now provide alkaline filters that reintroduce healthy minerals and improve taste, which is a major plus.

Wrap up

Using clean water is non-negotiable at home. This is why purchasing a tankless reverse osmosis system is a long-term decision for your home’s utility.

Choosing the ideal tankless RO system means finding the best quality for your home by providing better space and clean water. These top choices can offer maximum health benefits by ensuring quality water filtration systems.

It’s one step to caring for your well-being and making your home feel like a home.