Best Countertop & Portable Reverse Osmosis Systems: Reviews 2021

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Countertop reverse osmosis systems generally provide far better filtration than regular countertop water filters, removing up to 99% of all contaminants your water might contain.

Compared to most under sink reverse osmosis (RO) systems they may feature less filtration stages, but therefore countertop units don’t require installation. No drilling through your countertop or sink to accommodate the extra dispenser, no drain line connection, no nothing.

Countertop RO systems are either stand-alone or they can be hooked up to any standard kitchen faucet in seconds. This makes them perfect for renters who can’t make any changes to their plumbing and for everyone who simply doesn’t want to mess around with under-the-sink connections.

What’s more, some countertop reverse osmosis systems are tankless which means they deliver healthy and great-tasting drinking water on demand with only little space requirements – ideal for people living in a small home as well as students and travelers that are constantly on the move and want a highly portable water filter system to take with them.

Sounds great? Then let’s find you the best countertop/portable reverse osmosis system out there!

On This Page You Will…

No Time to Read? Check Our List of the Best Countertop and Tankless Reverse Osmosis Systems!

ProductsOur RatingPriceFilter StagesFiltered WaterNSF StandardsAnnual Cost
AquaTru 4-Stage Compact Countertop Reverse Osmosis System

Best Countertop Reverse Osmosis System: AquaTru

Read Review
$$$41 Gallon in 10-15 Minutes42, 53, 58, 401, P473~$100-120
Use our discount code BOSAquaTru at checkout and get 5% OFF!
Zero Installation Purifier – ZIP Compact Machine

The Runner-Up: Zero Installation Purifier

Read Review
$$$41 Gallon in 10-20 Minutes58~$75
Compact & Tankless RO System: Crystal Quest Thunder

Best Portable Reverse Osmosis System: Crystal Quest Thunder

Read Review
$$5 (10)~50 Gallons Per Day-~$65-100
Waterdrop WD-G3-W Tankless Reverse Osmosis System

Best Tankless Reverse Osmosis System: Waterdrop WD-G3-W

Read Review
$$$$31 Gallon in 3-4 Minutes58~$115

Countertop Reverse Osmosis System Reviews

1. Best Countertop Reverse Osmosis System: AquaTru (Including Coupon Code!)

In our opinion, the best countertop RO system in 2021 is the AquaTru. It’s independently tested and certified against 5 NSF standards (42, 53, 58, 401, P473) to remove up to 99.99% of 82 different water contaminants. In other words, it provides highly pure, safe, and great-tasting drinking water.

But the best thing about the AquaTru countertop RO system is that it’s a plug & play model that doesn’t require any kind of installation/plumbing – ideal for renters and to save money. On top of that, maintenance is a breeze and super low-cost. 4.5 stars!

Make sure to use our discount code BOSAquaTru at checkout and get 5% OFF!

AquaTru 4-Stage for table or counter top


Filter Stages:4
Purified Water:1 Gallon in 10-15 Minutes
NSF Certifications:42, 53, 58, 401, P473
Annual Cost:~$100-120

Our Rating


  • Countertop reverse osmosis system can be set up in less than 10 minutes without plumbing or drilling for maximum convenience.
  • It’s very easy to use and space-saving.
  • NSF certification standards 42, 53, 58, 401 and protocol P473 guarantee the most effective contaminant removal for healthy drinking water, e.g. chromium-6 (97.2%), cyst (99.99%), fluoride (93.5%), lead (99.1%), chlorine (96.6%), Ibuprofen (95.1%), Bisphenol A (99.0%), PFOA & PFOS (97.5%), VOCs (most >99%).
  • 4 stage filtration process:
    • Stage 1 + 2: Mechanical + activated coconut shell carbon pre-filter traps sediment like dust and other large particles, and adsorbs chemicals and bad taste & odor among other things.
    • Stage 3: RO membrane rejects impurities like fluoride, heavy metals, and overall TDS.
    • Stage 4: Activated coconut shell carbon block post-filter eliminates residual taste, pesticides, organic compounds, …
  • Fast filtration purifies a full gallon of water in 10 to 15 minutes, so no long waiting times.
  • A pressure pump increases water productivity and lowers reject water percentage.
    • 80% recovery rate means only 20% of water goes down the drain as wastewater (other reverse osmosis systems without a pump waste as much as 3-5 gallons of water for every gallon filtered).
  • Clean water can be dispensed via button push. Tank is portable and can be stored in refrigerator for cooling.
  • Wastewater collects in another tank and can be discarded.
  • Material is BPA and BPS-free Tritan plastic.
  • Filters last 600 gallons (6-12 months capacity) and reverse osmosis membrane lasts a full 1,200 gallons (2 years) for lowest maintenance requirements.
    • Cost are surprisingly affordable: About $100-120 per year.
  • Maintenance is straightforward thanks to tool-free replacement process and indicator light that tells you when to change the filters/membrane.
    • Takes barely 2 minutes.
  • The AquaTru countertop reverse osmosis water filter system is warranted for 1 year.


  • Potential leaking due to design flaw.
  • Some reviewers said their unit malfunctioned after a while.

→ Read Our Full AquaTru Water Filter Review Here

2. The Runner-Up: Zero Installation Purifier Countertop RO Water Filter – AlcaPure Edition

The Zero Installation Purifier is another stand-alone reverse osmosis water filter that doesn’t require installation. It’s just that we’re missing NSF certifications or testing (only the RO membrane is NSF 58 certified for several contaminants). Still, overall customer feedback is positive with people being most happy about the ease of use and great looks. 4 stars!

Zero Installation Purifier RO system for table or countertop

Alkaline RO Water Filter: Zero Installation Purifier

Filter Stages:4
Purified Water:1 Gallon in 10-20 Minutes
NSF Certifications:58
Annual Cost:~$75

Our Rating


  • Choose between Space Black and Silver White design. Both are nice.
  • This countertop RO machine is installation-free which is ideal for renters and if you don’t want to modify your plumbing or hire a plumber.
  • Very easy to set up and use. Simply fill water into the bottom tank and push start button.
  • 4 filtration stages remove up to 99% of contaminants.
  • Filter stage 1 is a 5-micron sediment filter. It traps sediment like sand and rust to prevent clogging of the rest of the system.
  • Filter stage 2 uses activated carbon filter block (coconut-based) to adsorb chlorine, disinfection byproducts, bad taste and odor, chemicals, etc.
    • Optional: Use the anti-scale carbon pre-filter if your water is very hard or high in TDS. Prevents scaling of the other stages for longer filter life span.
  • Filter stage 3 is the reverse osmosis membrane. It rejects heavy metals and other pollutants. NSF standard 58 certified.
  • Filter stage 4 combines carbon post-filter with remineralization.
    • Gives water a final polish removing residual contaminants.
    • Enriches water with healthy calcium and magnesium. Improves taste + balances pH (alkalinity).
  • Pressure pump boosts filtration speed and improves recovery rate to 50%.
    • It takes 10-20 minutes to process one gallon of water.
    • Only one gallon of water is wasted for every gallon of clean water (average RO system wastes 3-5 gallons).
  • Water tanks are BPA-free.
  • Maintaining the countertop unit doesn’t require much time or effort. A warning light reminds you to replace filters once a year. RO membrane has a capacity of 2-4 years.
    • Sediment filter and carbon pre-filter feature twist on/off mechanism. The other filter stages use quick-connect fittings.
    • Cost: About $75 per year which is hard to beat.
  • 1-year money-back satisfaction guarantee for peace of mind.
  • Covered by 1-year warranty.


  • It can be difficult to lock the feed tank in place so that the purification process won’t start or may cause leaking.
  • Some reviewers said their unit quit working entirely as it wouldn’t detect the feed water tank anymore.
  • Leaking from different parts of the system.
  • Some parts don’t feel very sturdy.
  • We’re missing NSF testing/certifications.

→ Read Our ZIP Zero Installation Purifier Review

3. Best Portable Reverse Osmosis System: Crystal Quest Thunder

In our opinion, the best portable reverse osmosis system in 2021 is the Crystal Quest Thunder. It’s not the only countertop model that’s installation-free but it’s probably the one with the highest portability. Plus, it doesn’t require electricity so it can be a great reverse osmosis system for camping if you have access to a standard-sized faucet. 4.5 stars!

Please note: The Crystal Quest Thunder misses NSF certifications with specific contaminant reduction rates which is why we prefer the AquaTru when portability is not a must!

Crystal Quest - Tankless Table or Counter Top Reverse Osmosis System

Crystal Quest Thunder

Filter Stages:5 (10)
Purified Water:Around 50 Gallons Per Day
NSF Certifications:
Annual Cost:~$65-100

Our Rating


  • The Crystal Quest Thunder portable 10-stage countertop reverse osmosis water filter system can be installed in no time – all hardware included.
  • Measuring 16x7x7 inches, it’s very compact and might even fit in your trunk when travelling.
  • Produces clean-tasting water.
  • Uses granular activated carbon (stage 2) to trap chlorine, pesticides, VOCs, bad tastes and odor, and more.
  • Uses RO membrane (stage 4) to reject most organic and inorganic contaminants.
  • Uses copper-zinc oxidation media (Eagle Redox Alloy, stage 6 + 7) to primarily reduce water-soluble metals such as lead, arsenic, and chromium. The blend also prevents bacterial growth inside the system.
  • Uses ion exchange resin (stage 8) to lower heavy metal content even further and also addresses water hardness.
  • Uses granular carbon post-filter (stage 9) to eliminate residual tastes.
  • A 1-micron filter pad before and after each filter stage blocks suspended solids and cyst.
  • Additional filter cartridges can be added to the countertop RO system.
  • Production is around 2 gallons of filtered water per hour so the system is probably best used in combination with a large container to eliminate long waiting times.
  • The filter elements are long-lasting which keeps maintenance at a minimum.
    • Replacement is fast and easy thanks to quick-connect fittings.
    • Cost: $65-100 per year, so not much!
  • Customer service is great.
  • 1-year warranty.
  • Reasonable price.


  • No data on performance or NSF certifications is provided.
    • Not that important with reverse osmosis systems unless you want to remove one or more specific contaminants.

→ Read Our Full Crystal Quest Thunder Review Here

4. Best Tankless Reverse Osmosis System: Waterdrop WD-G3-W

In our opinion, the best tankless reverse osmosis system in 2021 is the Waterdrop WD-G3-W. Sleek design, straightforward install, effortless filter replacements, and great water taste – people love this water filter which is not a countertop but an under sink unit. 4 stars!

Waterdrop WD-G3-W Tankless Reverse Osmosis Water Filtration System

Waterdrop WD-G3-W Tankless RO System

Filter Stages:3
Purified Water:0.28 Gallons Per Minute
NSF Certifications:58
Annual Cost:~$115

Our Rating


  • Tankless design saves a lot of space.
  • Internal pump increases pressure for 0.28 gallons per minute water flow.
    • One cup of water fills in about 12-13 seconds. No long waiting times!
    • Higher pressure also lowers the amount of wastewater going down the drain to one gallon for every gallon of filtered water.
  • Stage 1: Composite filter (polypropylene cotton + coconut shell activated carbon block) eliminates chlorine and large solids (sediment).
  • Stage 2: 0.0001-micron reverse osmosis membrane rejects heavy metals, bacteria among other microorganisms, fluoride, arsenic, and a lot more.
  • Stage 3: Another activated carbon block filter removes residual chemicals and tastes.
  • Tankless system was designed for 1 to 2-hour DIY install to save money.
    • Make sure to follow the provided instructions and helpful explainer videos found on YouTube.
  • All plastic is BPA-free to prevent contamination of the water.
  • Smart faucet uses built-in LED light to indicate filter status so no need to remember when to replace. Blue: Everything is good. Yellow: Less than 40 gallons or 15 days filtration capacity remaining. Red: Change one or more of the filters immediately.
    • Same indicator can be found on the system’s front panel.
    • TDS monitor also tells you about the condition of the filter elements.
  • Filters can be changed with a simple twist, no need for tools. Takes less than 10 seconds. Cost: About $115 per year.
  • Other features: Auto-flushing after 24-hour inactivity to prevent fouling and leak protector which shuts off the system if it detects continuous flow.
  • 30 days satisfaction guarantee.
  • 1-year manufacturer warranty (only when system is used with tap water).


  • Only NSF certification is Standard 58 for 94% total dissolved solids rejection. We would have preferred more thorough testing.
  • Some people have to drain about one gallon of water before the system reads TDS <30 ppm.
    • Might be a hardware of software error.

→ Read Our Full Waterdrop Reverse Osmosis Review Here

5. Bonus: PuroSmart – Smallest RO System

Still haven’t found the ideal countertop reverse osmosis water filter for your needs? Maybe you are looking for something a bit more tiny…

The PuroSmart is probably the smallest RO system of all. You might find it useful if the number one thing you lack in your home or kitchen is space, or if you’re constantly on the move and want a basic water purification system wherever you go.

Not small but mini: PuroSmart

Smallest RO System: PuroSmart

Filter Stages:2
Filtered Water:About 50 Gallons Per Day
NSF Certifications:
Annual Cost:~$50-125

Our Rating


  • The PuroSmart is easily the most compact countertop reverse osmosis water filter system we’ve ever seen. Length: 8.25 inches.
  • It’s convenient to use and doesn’t require permanent installation. Simply replace your kitchen faucet aerator with the diverter valve included in the package. Then mount the unit on the plastic stand and make the tubing connections. From now on you can enjoy clean and refreshing drinking water right from the tap!
  • A mini carbon block pre-filter removes chlorine. Capacity: 400 gallons or 3 months.
  • The RO membrane does its thing reducing TDS.
  • Produces up to 50 gallons of purified water per day at 60 psi feed pressure, according to manufacturer.
  • Comes with a limited warranty (one year).


  • We wouldn’t rely on this reverse osmosis system to produce water 100 percent safe for consumption.
  • The PuroSmart is more expensive that you’d think, both at initial purchase and when replacing the filter elements. Annual cost: $50-125.
  • We doubt that you’ll get 50 gallons of RO water out of this unit per day.

More Reviews

Buying Guide: Planning to Buy a Countertop Reverse Osmosis Water Filter? Consider This!

Faucet Connection

As a general rule, countertop water filters fit standard kitchen faucets only. Yes, there are adapters for bathroom taps and garden hoses etc., but if you are using a designer, pull-down, or sprinkler faucet that’s bad luck!

In any case, double-check that the faucet in question allows for a standard hose connection. If not, try to find a compatible adapter. By the way, most countertop reverse osmosis systems are shipped with a few adapters to try out.


We like to rely on certifications according to NSF standards. They guarantee that a certain water filter model or system is capable of removing/reducing a considerable amount of potentially harmful contaminants in water in addition to those affecting aesthetics.

Searching for the best countertop reverse osmosis water filter system, you should look out for NSF Standard 42 for water aesthetics, Standard 53 for contaminants with health effects, Standard 58 for further substances, Standard 401 for emerging contaminants, and NSF Protocol P473 specifically for the reduction of PFOA and PFOS.

Some of the standards also cover a product’s material safety and structural integrity.

Water Pressure & Wastewater

Reverse osmosis systems without a built-in pressure pump rely entirely on the water pressure in your home’s pipes to force water through their different filter stages. This has the benefit that no extra power supply is needed.

What might come in handy on a camping trip can be an issue if the water pressure in your home is too low. Because low water pressure not only results in a slow flow rate, it also increases the amount of wastewater going down the drain.

To be more precise, the filtered to drain water ratio declines: Under normal conditions and without applying a pump, reverse osmosis systems waste 2 to 4 gallons of water for every gallon that you can drink or use otherwise. In cases of extremely low pressure, this ratio can increase to 1:6 or even 1:8.

Most systems tend to perform best at around 65 psi. Anything less than 35 psi is considered insufficient.

pressure gauge

Flow Rate

Simply put, filter systems producing water on demand should have a high enough flow rate to avoid long waiting times.

Maintenance (Cost)

Countertop/tankless RO water filters are low in maintenance, so no need to worry about that. What you should pay attention to, however, is maintenance cost.

While some units are more expensive to purchase, they might be cheaper to maintain, and vice versa. So don’t forget to check the cost, capacity & longevity, and availability of replacement filter elements. (Of course, that’s exactly what we did with each product reviewed above!)


Do yourself a favor and don’t choose the ugliest system if it’s going to sit on the top of your counter for the next 5 to 10 years.

More on Countertop Reverse Osmosis Systems

What is a Countertop Reverse Osmosis System?

Simply put, a countertop reverse osmosis system is a device for filtering tap water and make it ready for drinking. As the name suggests, countertop RO systems rely on reverse osmosis filtration technology to remove up to 99% water contaminants, including chlorine, chromium, lead, fluoride, microorganisms, chemicals, and much more. In other words, they are highly, highly effective.

Apart from reverse osmosis filters that sit on the countertop, there’re under sink units and whole house systems.

Countertop models are either stand-alone or they connect to a faucet. Furthermore, we can differentiate between on-demand systems and those featuring a tank to store the filtered water in.

Filtered water flow: Anywhere between 2 to 6 gallons per hour.

How Does a Countertop RO Filter Work?

Countertop RO systems are either fed through a faucet connection or they have a feed water tank that requires manual refilling. Once in the system, the feed water goes through several filtration stages – the specific setup varies from model to model – before it’s ready for dispensing. Here’s what a typical filtration process looks like:

  1. The first filter stage is usually a sediment pre-filter. It protects the rest of the system from clogging.
  2. Next comes an activated carbon filter, either granular or block. The carbon adsorbs chlorine, bad taste and odor, VOCs as well as other chemicals, and discoloration.
  3. At the heart of the system is the reverse osmosis membrane which rejects 98-99% of all total dissolved solids. It does the bulk of the contaminant removal.
  4. A second coconut shell GAC stage filters residual tastes.
  5. Some systems make use of remineralization. It releases calcium and possibly other minerals into the water which improves taste and balances pH.

Reverse Osmosis Process Diagram

Reasons to Invest in a Table Top RO System: Advantages (& Limitations)


  • Reverse osmosis water filtration is a tried and tested technology. It removes up to 99.99% of hundreds of different contaminants that could be present in your water supply giving you access to safe and healthy drinking water.
  • Filtration speed is solid.
  • Setting up a countertop RO unit takes no more than a few minutes and doesn’t involve plumbing or drilling. The non-permanent installation is great if you’re a renter.
  • System maintenance is nice and easy, and affordable!
  • All countertop reverse osmosis water filter systems are compact. And some are even suited for travelling.
  • Reverse osmosis doesn’t rely on electricity. All you need is a standard-sized faucet with enough water pressure.


  • Units fit standard kitchen faucets only.
  • Some people don’t like the taste of RO water.
  • Reverse osmosis produces wastewater.

Setting Up a Countertop RO Unit

In the introduction we mentioned that you can connect almost any countertop water filter system to a standard kitchen faucet within minutes.

Instead of describing the process step-by-step we thought why not insert a quick video to show you:

Small, Compact & Tankless – Perfect for Camping?

Tankless reverse osmosis water purifiers are perfect for camping because they’re small and compact a.k.a. easily portable.

Now you might be thinking, why would I use a water filter when I’m in the great outdoors? I can either bring bottled water, or I drink the water Mother Nature provides me with. Yeah, well…

  • Natural and man-made water contamination does not stop at creeks, ponds, lakes or any other surface or groundwater source.
  • Most bottled water is literally nothing but municipal tap water filled into a bottle.

So remember: Whenever you go on a camping trip and there’s a standard-sized faucet, always take your portable RO filter system with you.

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I hope this list of the best countertop reverse osmosis systems was helpful. Questions? Ask away!

And keep in mind: We’ll add new countertop reverse osmosis water filter reviews occasionally. So come back for more!

About the Author Gene Fitzgerald

Gene Fitzgerald has been with BOS since the very beginning. She is head of content creation and has fully immersed herself into the home water treatment industry only to become an expert herself. Outside of BOS, Gene loves reading books on philosophy & social issues, making music, and hiking.
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