Affiliate Disclosure:This Old House’s Reviews Team is committed to delivering honest, objective, and independent reviews on home products and services. To support this business model, This Old House may be compensated if you purchase through links on our website.
Investing in and installing a reverse osmosis water filter gives you cleaner, more pure water by removing dirt, chemicals, microorganisms, heavy metals, and other contaminants and impurities.
Our team has found the best reverse osmosis systems on today’s market to fit your sink. These are our top picks.
Top 6 Reverse Osmosis Systems
- Best Reverse Osmosis System Overall: iSpring 6-Stage Reverse Osmosis System
- Best Undersink Reverse Osmosis System: Express Water RO5DX 5-Stage Under Sink RO System
- Best Tankless Reverse Osmosis System: Waterdrop G3P600 8-Stage Tankless RO System
- Best Drinking Water Filtration System: APEC Water Systems ROES-50 5-Stage RO System
- Best Countertop Reverse Osmosis System: AquaTru 4-Stage Countertop RO System
- Best Budget Reverse Osmosis System: Whirlpool WHAROS5 RO Water Filtration System
Compare Top Reverse Osmosis Systems
| Product | Capacity | Filtration Stages | NSF Status | Installation | Warranty |
|---|---|---|---|---|---|
| iSpring RCC7AK 6-Stage Reverse Osmosis System | 75 GPD | Six | NSF certified | Under-sink | 1 year |
| Express Water RO5DX 5-Stage Under Sink RO | 50 GPD | Five | NSF Certified | Under-sink | 1 year |
| Waterdrop G3P600 8-Stage Tankless RO System | 600 GPD | Eight | NSF Certified | Under-sink | 1 year |
| APEC Water Systems ROES-50 5-Stage RO System | 50 GPD | Five | Not certified | Under-sink | 1 year with 2-year available upon registration |
| AquaTru 4-Stage Countertop Water Filter System | 1 gallon tank | Four | NSF Certified | Countertop | 1 year |
| Whirlpool WHAROS5 RO Water Filtration System | 50 GPD | Five | NSF Certified | Under-sink | Lifetime |
| Product | Capacity | Filtration Stages | NSF Status | Installation | Warranty |
Best Reverse Osmosis System: iSpring 6-Stage RO System
iSpring 6-Stage Reverse Osmosis System
- $279
Prices taken at time of publishing.
Pros and Cons
✔ Comes with a 100% satisfaction guarantee from the manufacturer
✔ Includes instructional videos and customer support to make the installation process easier
✔ Has a fine reverse osmosis membrane
✘ Some customers have mentioned leaking
✘ Has been issued a Proposition 65 warning from the California government, indicating that it may expose users to chemicals
What Customers Are Saying
Our team found that customers frequently complimented how easy to install this system was, with the process being easy enough for even those with no DIY experience to manage. Reviewers who rated this product poorly complained that the system’s parts leaked.
Best Undersink Reverse Osmosis System: Express Water 5-Stage RO System
Express Water 5-Stage Reverse Osmosis System
- $199.99
Prices taken at time of publishing.
Pros and Cons
✔ Has a high temperature rating of 100 degrees Fahrenheit
✔ Has a lightweight body that’s ideal for fragile plumbing systems
✔ Can be customized with add-ons, such as deionization filters
✘ Has a slower water recovery than competing systems
✘ Some customers said that the water storage tank broke down
What Customers Are Saying
Our team noticed that customers praised this RO’s filter design because the swivel connections allowed for quick-change filters without removing any tubing. However, dissatisfied customers complained about the system’s maintenance process, which required regular intensive cleaning in addition to filter changes.
Best Tankless Reverse Osmosis System: Waterdrop 8-Stage RO System
Waterdrop 8-Stage RO System
- $645.99
Prices taken at time of publishing.
Pros and Cons
✔ Comes in multiple finishes
✔ Comes with water filter system detection that tells you when the filter needs to be replaced
✔ Offers a massive water flow rate of up to 600 gallons per day (GPD)
✘ Is priced significantly higher than many other systems
✘ Has a heavier weight than most competing models
What Customers Are Saying
Customers praised this system’s effectiveness. Several customers purchased tap water testing kits to determine the efficiency of this system and found that the water it provided was comparable to filtered bottled water. However, we also saw that some customers found its faucet to be flimsy.
Best Drinking Water Filtration System: APEC 5-Stage Reverse Osmosis System
APEC 5-Stage Reverse Osmosis System
- $199.95
Prices taken at time of publishing.
Pros and Cons
✔ Comes with everything you to need to install it, including a drain saddle and food-grade tubing
✔ Can purify mineral-rich well water
✔ The fittings have stainless steel teeth for gripping
✘ Not NSF certified
✘ Requires power tools for installation
What Customers Are Saying
Reviews we found complimented the efficiency of this system, which multiple customers said saved them more energy and money than previous reverse osmosis systems they had used. However, some customers weren’t satisfied with the system’s installation process, which required a cordless drill to drill holes.
Best Countertop Reverse Osmosis System: AquaTru 4-Stage Reverse Osmosis System
AquaTru 4-Stage Reverse Osmosis System
- $449
Prices taken at time of publishing.
Pros and Cons
✔ Doesn’t require plumbing installation
✔ Uses specialty filters that may last up to two years before a replacement filter is needed
✔ Purifies 1 gallon of tap water in as little as 12 minutes
✘ Provides four stages of filtration, which is fewer levels than the other options in this review
✘ Priced higher than many direct-connection systems
What Customers Are Saying
Customers we found said that this reverse osmosis system was strong enough to remove even solid particles from the gallons of water it filtered. However, customers who weren’t satisfied with their purchase complained that it stopped working after a short period of time.
Best Budget Reverse Osmosis System: Whirlpool Reverse Osmosis Water Filtration System
Whirlpool Reverse Osmosis Water Filtration System
- $147
Prices taken at time of publishing.
Pros and Cons
✔ Has an EZ-change indicator light that tells you when it needs to be changed
✔ Includes easily removable filters
✔ Can remove up to 15 contaminants
✘ Has a bulky design
✘ Wastewater rates are not indicated
What Customers Are Saying
We found that customers who were impressed with this product particularly liked that it was easy to install, made for great-tasting clean water, and that it produced quick results. On the other hand, we also saw some customers who felt that some of the parts were not high quality, and others said the filter needed to be changed out too frequently.
Buying Guide To Whole House Reverse Osmosis Systems
A reverse osmosis water filtration system is an easy form of water treatment. It works by removing contaminants from your tap water during the filtration process. We put together this buying guide that will help you pick the best reverse osmosis system for your sink.
Filtration System Size
Reverse osmosis systems can vary greatly in size. Most models we examined are designed to be stored underneath a sink, although countertop versions also exist. Measure how much space you have under or around your sink before purchasing a reverse osmosis system.
Reverse Osmosis Tank
Some RO filtration systems have a tank that stores water before it’s transferred to your sink. Others forgo the tank to save space. The type you purchase should depend on how much space you have in your kitchen.
Water Filter Type
Reverse osmosis systems move water through three to eight filters to remove contaminants. Common types of filters we found include:
- Sediment: This type of filter removes dirt and other large particles.
- Carbon: This type removes chlorine.
- Reverse osmosis: These filters remove particles that are larger than water molecules.
- UV: This type of filter kills microorganisms.
- Targeted: These filters remove specific types of contaminants, such as nitrate or fluoride. They’re only needed if these contaminants are present in large quantities.
- Remineralization: This filter introduces calcium and magnesium into the purified water to balance its pH.
Capacity
The amount of water that a reverse osmosis system can purify at one time is typically measured in gallons per day, or GPD. Choose a capacity based on how much water you and your family use in a day. For example, if you live alone, a system that purifies four gallons of water will be enough. However, if you have a family of five, you will need a reverse osmosis system that can purify at least 20 gallons of water.
Safety Features
We’ve found that some reverse osmosis systems have built-in features to ensure that they run smoothly. Common features we noticed include leak detectors and filter replacement indicators.
Water Pressure
In order for a reverse osmosis water filter to work properly, our team found it should have at least 50 PSI. RO water filters with above an 80 PSI are ideal for homes where the water supply lacks pressure.
How To Install a Reverse Osmosis Filter
While you can always hire a professional to install a reverse osmosis filter in your home, passionate DIYers can also try it on their own if they have the right materials, including an adjustable wrench, pencil or marker, screwdriver, and drill.
In the video below This Old House’s Richard Trethewey takes you through the step-by-step process of installing a reverse osmosis filter to remove impurities from your home’s water.
What is an NSF Certification?
National Sanitation Foundation (NSF) is an independent, third-party certification organization that tests and certifies products and services to ensure they meet certain public health and safety standards.
When a water filter is NSF certified, it means that it has been tested and found to meet or exceed specific performance standards for the reduction of a variety of contaminants, such as lead, chlorine, bacteria, and other impurities. This can provide peace of mind to consumers, knowing that the filter they are using has been independently verified to be effective at removing potentially harmful substances from their drinking water.
Furthermore, many government agencies and organizations require NSF certification for water filters to ensure that they meet specific standards for public health and safety. For example, many states require NSF certification for water filters used in schools, hospitals, and other public facilities.
Frequently Asked Questions About Reverse Osmosis Systems
How does a reverse osmosis system work?
A reverse osmosis system removes dirt, bacteria, and chemicals from your drinking water. It does this by passing water through a series of filters that each target a specific contaminant. Since the filters are semipermeable membranes, they allow water to pass through them while trapping undesirable molecules. The resulting water is purer than standard tap water.
Why do I need a reverse osmosis system?
A reverse osmosis system can provide your whole house with healthier and better-tasting water. However, our team notes that it’s especially important to use a reverse osmosis system if you live in an area with poor water quality.
How often do I need to replace the filters in my reverse osmosis system?
In our experience, you should replace the filters in your reverse osmosis system at least once per year. If a filter gets clogged or damaged, replace it sooner. Some reverse osmosis systems have warning systems that tell you when a filter is failing or nearing the end of its life.
More Tap Water Products
Why You Can Trust Us
This Old House has empowered homeowners for more than four decades with top-notch home improvement content in the form of television programs, print media, and digital content on its website and social media platforms. Our small team focuses on creating in-depth product and service review content to help inform your purchasing decision for just about any item or resource that you might need for your home. To date, we have written over 1,000 reviews on products in the home space, from cordless drills to kitchen trash cans, lawn mowers, and dining room decorations.
We recommend products in each review using an intensive research process, spending hours combing through the best available models. For a product to make our list of top picks, it must hold a solid sales record, have consistently positive customer reviews, and offer unique features, among other factors. After narrowing down our list of recommendations, we conduct additional research and sometimes in-person testing to ensure that the products meet our standards. Once we conclude the research phase, we craft a well-rounded, user-friendly article that includes our recommended products and additional information to help homeowners like you make the right purchase.
To share feedback or ask a question about this article, send a note to our Reviews Team at reviews@thisoldhousereviews.com.