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Our Verdict (Best For)
The Brondell H20+ Circle seems like the perfect under sink RO at first: It has a well-made design that is exceptionally easy to set up since most of the parts are housed in the unit. It’s also easy to prime, use, and maintain. Plus, for a tank-based system, overall water waste is low thanks to the smart valve and circular reservoir. And most importantly, the Brondell had excellent results in our lab testing, it holds NSF certification for 61 contaminants, and its filtered water tasted and smelled flawless. However, faucet flow is pretty slowly compared to the competition – one reason why Amazon reviews are mixed (some people reported their flow being just a trickle). Other complaints include faulty parts and overall quality issues. Considering the high price tag (annual filter cost is average), we think the Brondell H20+ Circle is solid but there are better options out there.
The Brondell H2O+ Circle is a tank-based under sink reverse osmosis system that requires a plumbing connection. It’s designed for use as a drinking water filter and can purify both tap water and properly disinfected well water (pre-treatment may be required).
As usual, we’ve tested the system with our own hands:
- Hands-on experience: We installed/assembled, used, and maintained it.
- Filtration effectiveness: We sent an unfiltered and a filtered tap water sample to a professional lab for analysis in order to determine real-life contaminant reduction capabilities. Plus, we checked for NSF certifications and other test data.
- More testing: We performed a taste & odor test, a filtration speed test, a tank-filling speed test, a usable water test, and a wastewater test.
- All other product aspects: We considered initial + long-term cost, product warranties, additional features, frequent customer complaints, etc.
Contents
Final Rating: /5.00
Filtration: /5.00
Usability: /5.00
Costs: /5.00
| Type: | Under Sink Reverse Osmosis System |
| Price (May 5, 2025 No Short-Term Sales): | $449.99 |
| Yearly Cost for 1,000 gal Based on Rated/Claimed Filter Life (May 5, 2025): | ~$205 |
Final Rating: /5.00
What We Like Most
- Achieved excellent results in our lab testing for contaminant reduction.
- Filtered water tasted and smelled flawless.
- Almost fully NSF-certified for contaminant reduction.
- Very easy to set up, with most of the parts housed inside the unit; also easy to prime.
- Easy to use and maintain providing plenty of filtered water.
- Sleek, well-made design and simple but solid faucet.
- Smart valve and circular reservoir result in very low water waste for a tank-based RO system without pump.
- Automatic flushing helps extend RO membrane lifespan.
- Filter life indicator (faucet).
What We Don’t Like
- Very slow to dispense water (but reasonable speed in filling the tank).
- Automatic flushing wastes additional water.
- Expensive up-front cost (but pretty average annual maintenance fees).
- Notable percentage of negative Amazon reviews (mostly complains about faulty parts, slow flow, quality issues, and system not lasting).
How the Brondell H2O+ Circle Compares to…
10 Other Under Sink Reverse Osmosis Systems
In this video, Sara highlights our under sink RO top picks. The Brondell H2O+ Circle was included in our testing, but didn’t make the cut.
Please note: Our full guide on the best under sink reverse osmosis systems is available here.
Video Chapters + Comparison Sheet
- Link to Comparison Sheet
- 00:00 – Intro
- 00:22 – What’s New?
- 01:11 – Our 11 Under Sink ROs
- 01:54 – How We Tested & Rated
- 05:08 – Our Recommendations
- 06:11 – Best Overall (Cloud RO)
- 20:57 – 2 Best Tankless Units (Waterdrop G3P600 & X12)
- 35:38 – Highest Filtration Score (Aquasana SmartFlow)
- 37:22 – Made in USA (USWS All American & Home Master TMHP-L)
- 41:28 – Budget Pick (APEC ROES-50 Essence)
- 42:50 – Summary
18 Other Under Sink Water Filters
In this video, Sara highlights our under sink water filter top picks. The Brondell H2O+ Circle was included in our testing, but didn’t make the cut.
Please note: Our full guide on the best under sink water filters is available here.
Video Chapters + Comparison Sheet
- Link to Comparison Sheet
- 00:00 – Intro
- 00:34 – How We Tested & Rated
- 01:53 – Our Recommendations
- 03:01 – Best Overall (Cloud RO)
- 15:11 – 2 Best Tankless ROs (Waterdrop G3P600 & X12)
- 27:26 – Best Non-RO Filter (Epic Smart Shield)
- 31:22 – Highest Filtration Score (Aquasana SmartFlow)
- 32:02 – Made in USA (USWS All American & Home Master TMHP-L)
- 32:34 – Budget RO Pick (APEC ROES-50 Essence)
- 32:51 – AO Smith AO-US-200 & Culligan US-EZ-4
- 33:34 – Summary
Full Analysis of the Brondell H2O+ Circle
Filtration: /5.00
1. Lab Results: /5.00
Remember that our before vs after lab comparison is not an exact science. It’s informational and subject to variability, inaccuracies, and interferences caused by natural fluctuations in water quality, accidental contamination, human error, instrumentation issues, and more. Furthermore, our lab-testing is limited to those contaminants present in our water supplies and at their respective concentrations. As such, it can only give us a general idea for how effective a certain water treatment product might be.
Lab Results Chart
| Potentially Harmful | Aesthetic Issues | Feed Water Level | Filtered Water Level | Reduction Rate | |
| Water Disinfectants | |||||
| Chlorine (mg/L) | ✖ | ✖ | 0.68 | 0 | 100% |
| Disinfection Byproducts | |||||
| Bromodichloromethane (µg/L) | ✖ | 0.99 | 0 | 100% | |
| Bromoform (µg/L) | ✖ | 1.17 | 0 | 100% | |
| Dibromochloromethane (µg/L) | ✖ | 1.4 | 0 | 100% | |
| Chloroform (µg/L) | ✖ | 0.78 | 0 | 100% | |
| Metals | |||||
| Copper (mg/L) | ✖ | ✖ | 0.08 | 0 | 100% |
| Iron (mg/L) | ✖ | 0.04 | 0 | 100% | |
| Aluminum (mg/L) | ✖ | ✖ | 0.01 | 0 | 100% |
| Barium (mg/L) | ✖ | 0.04 | 0 | 100% | |
| Boron (mg/L) | ✖ | 0.09 | 0.02 | 78% | |
| Zinc (mg/L) | ✖ | 0.01 | 0 | 100% | |
| Strontium (mg/L) | ✖ | 0.46 | 0.01 | 98% | |
| Salts | |||||
| Nitrate (N) (mg/L) | ✖ | 1.73 | 0 | 100% | |
| Fluoride (mg/L) | ✖ | 0.41 | <0.1 | Anywhere Between 76% and 99% | |
| Other | |||||
| Uranium (µg/L) | ✖ | 1 | 0 | 100% | |
| RO Salt Rejection | |||||
| TDS (mg/L) | ✖ | 303.6 | 16.8 | 94% | |
| Impurities NOT Detected in Unfiltered Tap Water Sample | |||||
| Explanation: | |||||
| Full Removal | |||||
| Considerable Reduction | |||||
| Concentration More Than Double of Unfiltered Water Sample | |||||
| Potential Leaching Reached or Exceeded the Strictest Public Health Guideline We Could Find | |||||
*100% means reduction to below the minimum detection level. To learn more about our testing procedures check our editorial guidelines.
Link to Filtered Water Report
Link to Unfiltered Water Report
Usability: /5.00
Costs: /5.00
Please note: This page is still a work in progress. Additional content and details will be added shortly – stay tuned!
About the Author(s)
Sara has been a lifelong home-improvement fan (she’s been hooked on This Old House since she was five) and taught herself any project she didn’t already know by watching YouTube tutorials. She is also an award-winning filmmaker. Armed with this skillset, Sara installs, primes, samples, uses, and maintains nearly every point-of-use water treatment systems we test – then brings her results to life on camera for our YouTube channel.
Raoul has a background in mechanical engineering and has been writing about home water treatment since 2015. He designs our product review processes, analyzes the results, and ties everything together. As editor-in-chief, he tries hard to keep the whole operation running smoothly behind the scenes.