If you want access to filtered water directly from a kitchen or bathroom faucet, the This Old House Reviews Team is here to help. We researched the best under-sink water filters and created a buyer’s guide to help you make an informed purchase. Here are our top water filter recommendations.
Top 5 Under-Sink Water Filters
- Best Filter Life: CuZn Under-Counter Water Filter
- Most User-Friendly: Filtrete Under-Sink Water Filtration System
- Best Design: Express Water Under-Sink Filtration System
- Most Versatile: Waterdrop Under-Sink Water Filter System
- Best Two-Stage Filter: FRIZZLIFE Under-Sink Water Filter
Best Filter Life: CuZn Under-Counter Water Filter
Pros and Cons
✔ Designed to attach to your kitchen sink’s cold water line✔ Uses a catalytic carbon filter that’s resistant to mold and bacteria growth✔ Can last up to five years✘ Doesn’t specify if it has an NSF certification✘ Not designed to help with hard water
Under-Sink Water Filters Comparison
CuZn Under-Counter Water Filter
- $150
- $200
- 26% off
Prices taken at time of publishing.
This under-sink water filter uses a three-stage filtration system that’s made of layers of activated carbon, micro sediments, and copper-zinc granules. It has a lifespan of up to five years per cartridge. Plus, it’s easy to install, connecting directly to your kitchen sink’s cold water line.
What Customers Are Saying
Satisfied customers were pleased with this product’s easy-to-follow installation instructions. Many said that the filter improved their water by removing its chemical taste and smell. However, unsatisfied customers were skeptical that this under-sink water filter truly filtered their water effectively.
Most User-Friendly: Filtrete Under-Sink Water Filtration System
✔ Meets the National Science Foundation (NSF) Standard 42, which proves that it filters out certain types and amounts of contaminants✔ Coordinates with your existing kitchen faucet✔ Has a lower price point than some other models
Filtrete Under-Sink Water Filtration System
- $41
- $60
- 32% off
This under-sink water filter is efficient, removing sand, rust, and other sediment that’s larger than 0.5 microns. This system uses replaceable filters that last up to six months and install using a simple quarter turn. Additionally, this filter attaches directly to your existing sink.
✘ Some customers felt the pressure level was too high✘ Has a lower filter life than some other models
Positive reviews highlighted how easy this product was to install. Customers also said that it improved the flavor of their water and the flow of their water from their kitchen sink. Negative reviews pointed out that this under-sink water filter caused flooding and had too much pressure.
Best Design: Express Water Under-Sink Filtration System
✔ Filters 50 gallons of water per day✔ Features a detection system that automatically shuts off the filter ✔ Includes on-demand support
Express Water Under-Sink Filtration System
- $163
This under-sink filter produces clean drinking water using reverse osmosis, which uses a partially permeable membrane to separate up to 99.99% of lead, nitrates, chlorine, and other contaminants from your water. The manufacturer also offers on-demand support.
✘ Has a higher price point than other under-sink water filters✘ Some customers found it challenging to find replacement water filters
Many reviewers noted that the instructions they received with their reverse osmosis system made installation easy. Positive reviews also highlighted that the quality of their water was immediately improved. On the other hand, unhappy customers complained about how difficult it was to find a compatible replacement water filter.
Most Versatile: Waterdrop Under-Sink Water Filter System
✔ Filter can last for up to two years✔ Uses an activated carbon filter that improves the taste and smell of your water✔ Replacing the filter only takes three seconds✘ Some customers said the filter stopped working after a few months ✘ Has a low flow rate of 0.75 gallons per minute
Waterdrop Under-Sink Water Filter System
- $70
- $94
- 26% off
This under-sink water filter has a simple design that makes it easy to install in a variety of ways, including with your existing kitchen faucet. This under-sink water filter removes dangerous contaminants with its NSF-certified design while retaining essential minerals.
Customers who were pleased with their purchase thought that this filter was easy to install, with some saying that it only took 10 minutes. Other reviewers noted that the flavor and clarity of their water were significantly improved. Dissatisfied customers pointed out that the water flow was weak and that the system stopped filtering after a few months.
Best Two-Stage Filter: FRIZZLIFE Under-Sink Water Filter
✔ Removes contaminants from over two gallons of water per minute✔ Takes less than three minutes to install✔ Reduces levels of carcinogens, mercury, and rust
FRIZZLIFE Under-Sink Water Filter
- $70
- $100
- 31% off
This two-stage filter uses a high-efficiency process that removes contaminants while also improving the smell and taste of your drinking water. It removes over 99.99% of contaminants from over 1,600 gallons of water in its lifetime while leaving healthy minerals.
✘ Some customers said it began leaking shortly after installation✘ Warranty length not specified
Positive reviews said that this under-sink water filter was well-packaged and easy to install and immediately improved their water’s flavor. Other reviews noted that its cartridge was easy to replace and reasonably priced. Negative reviews criticized this product for leaking, not being durable, and not filtering their water effectively.
Buyer’s Guide
When purchasing a water filter, it’s important to consider how its specifications and design impact its performance. Here are three factors to think about as you’re buying an under-sink water filter:
- Filtration process
- Flow rate
- Water pressure
Filtration Process
Most under-sink water filters purify water through a carbon filter or reverse osmosis. Models with carbon filters purify water by absorbing contaminants. While carbon filters make under-sink water filters more affordable, they don’t remove all contaminants.
Some under-sink water filters use reverse osmosis to filter water. Reverse osmosis filters purify water by using pressure to force the water through a semipermeable membrane. This leaves behind contaminants, preventing them from reaching the purified side. While this is more effective than carbon, you can still get a quality carbon filter, especially since most under-sink water filters use multiple layers of filtration to provide clean drinking water.
Flow Rate
An under-sink water filter’s flow rate is determined by how many gallons of water it can purify per minute. This number varies depending on the filter’s filtration method and size. For example, the FRIZZLIFE Under-Sink Water Filter filters two gallons per minute (GPM), while the more narrow Waterdrop Under-Sink Water Filter System filters 0.75 GPM.
Water Pressure
An under-sink water filter’s water pressure impacts its filtration process, as low water pressure inhibits the filtration process. To ensure that their systems are operating at the proper water pressure, many models include water pressure gauges for easy monitoring.
Frequently Asked Questions
What’s the benefit of an under-sink water filter?
Under-sink water filters simplify water purification by filtering water at its source, removing the need to use water-purifying pitchers.
How much does an under-sink water filter cost?
The price of an under-sink water filter depends on a number of factors, including its filtration method and size. However, most filtration systems cost between $50 and $100.
How long does the cartridge in an under-sink water filter last?
Most under-sink water filters require a replacement cartridge every six to eight months of use.
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