What’s more, this water filter has the fastest flow rate of all the filters on our list, powering through a half-gallon of water every minute, so you’re not stuck waiting on clean water. The filters are very economical—they last for up to six months or 800 gallons, meaning you pay less than 10 cents per gallon filtered. However, those with limited cabinet space may want to consider another system on this list, as this under-sink water filter takes up a lot of space. Keep in mind that the system will not reduce total dissolved solids (TDS). The included metal faucet is available in brushed nickel, chrome, and oil-rubbed bronze, so you can choose which will best match your existing kitchen hardware and decor. Price at time of publish: $450Product Details:
Filter Type: Sediment pre-filter, activated carbon filter, and catalytic carbon filterFilter Capacity: 800 gallonsNSF-Certified: Yes
Whom it isn’t for: People who want their water to go through multiple levels of filtration. A budget-friendly option that’ll comfortably fit in any cabinet, the EcoPure Main Faucet Filtration System filters chlorine, sediments, and cysts incredibly effectively, and the easy installation means there’s no reason to get a professional involved. It uses a carbon-spun fiber filter to reduce contaminants, but due to its compact size, water only goes through one stage of filtration. Price at time of publish: $51Product Details:
Filter Type: Carbon-spun fiberFilter Capacity: N/A change filter every six monthsNSF-Certified: Yes
Whom it isn’t for: People who need to filter well water.The Waterdrop filtration system takes your tap water through a whopping eight stages of filtration, including a cotton layer to reduce large particles, an activated carbon filter for removing residual chlorine and odors, and more. However, the most important step in the filtration process is the reverse osmosis system, which reduces over 90 percent of TDS, in addition to heavy metals such as lead, arsenic, mercury, and cadmium. It’s also certified NSF 58 for TDS reduction and certified NSF 372 for lead-free material. And given the extensive filtration of this system, it offers a relatively fast flow rate: it can filter a cup of water in about 12 seconds. Unlike many other RO systems, the Waterdrop filters water on demand without a tank, so it takes up less space in your cabinet. Reverse osmosis systems are also notorious for creating a lot of water waste (as much as four gallons of water “rinse” per one gallon of filtered water). Fortunately, the Waterdrop system has a drain-to-filtered water ratio of 1:1, significantly reducing water waste (and your water bill). The system comes with a smart and stylish faucet with a built-in LED display that will alert you as to when it’s time to change the filter and display the quality of your filtered water. The reverse osmosis replacement filters run for nearly $90, but fortunately, they only need replacing every two years. If you can swing it, the Waterdrop Reverse Osmosis Drinking Water Filtration System will leave you wanting for nothing. Price at time of publish: $646Product Details:
Filter Type: Reverse osmosisFilter Capacity: 400 gallonsNSF-Certified: Yes
Whom it isn’t for: People who tend to forget to replace the filter.This reverse osmosis option is a little different from the Waterdrop G3 Reverse Osmosis Water Filter System in that it’s not as heavy duty (it doesn’t remove as many contaminants as the Waterdrop option), and it’s significantly more affordable. Unlike most of the other under-sink water filters on this list, it doesn’t have a specific amount of water it can filter before you change the cartridge: In this case, you just have to swap it out every six months. Since there’s no auto-off function, you’ll have to remember to do that on your own, so if you’re the forgetful type, it might not be the best option for you. Price at time of publish: $194 Product Details:
Filter Type: Reverse osmosisFilter Capacity: N/A, change filter every six monthsNSF-Certified: Yes
Whom it isn’t for: People who don’t want to hire a professional to install their water filter. This option is best suited for well water due to its advanced, dual-stage carbon block filtration system that removes heavier, larger contaminants from the water—such as particulates, chlorine taste and odor, lead, turbidity, parasitic protozoan cysts, VOCs, and methyl tert-butyl ether (MTBE). It has a large filter capacity of 625 gallons and a quick-change cartridge design, so you don’t have to turn off the entire system when it’s time to swap filters out. You will, however, need to professionally install this option, and it won’t help reduce mercury levels in water, in case that’s a concern for you. Price at time of publish: $395Product Details:
Filter Type: Carbon blockFilter Capacity: 625 gallonsNSF-Certified: Yes
How to Shop for an Under-Sink Water Filter Like a Pro
Type
The type of filter(s) plays an important role in both the price and effectiveness of an under-sink water filtration system. There are generally three different types of filters available on the market, and the one you pick will most likely depend on your budget and the type of filtration you need. Here’s a quick primer on the different types of water filters:
Carbon Filter: A carbon filter is the most basic option when it comes to filtration, but still very effective. In this case, activated carbon will chemically bond with contaminants, removing them as water flows through the filter. However, all carbon filters aren’t created equal, so the effectiveness of a carbon filter alone will vary. You should look for the level of filtration noted on the product, including the contaminants it will remove.Reverse Osmosis Filter: The most heavy-duty option, reverse osmosis systems flush contaminants from the water supply to deliver filtered water through a separate faucet. The system works by pushing water through a membrane with pores that are incredibly small, so that only water molecules can pass through. That makes reverse osmosis filters the most effective, with the ability to eliminate thousands of toxins such as chlorine, fluoride, and heavy metals, as well as bacteria and pesticides. However, many take up a considerable amount of cabinet space and are pretty difficult to install, which means you’re better off relying on a professional.Ultrafiltration: Ultrafiltration uses a hollow fiber membrane to stop debris and contaminants from entering the water. It’s not as effective as a reverse osmosis system, but it can preserve the healthy minerals that are eliminated in systems where only water molecules pass through. These systems are also easier to install, as they generally work as an addition to the existing faucet. However, in these cases, the filters will need to be changed much more often.
Filter Replacement
“Most filters need to be swapped every six months and cleaned periodically,” says Pinchev. “Due to this, I would recommend looking for options where the filters are relatively cheap and easy to purchase, and also allow easy access, so they can be cleaned without tearing the whole system apart.” After all, there’s nothing worse than buying an under-sink water filtration system, only to realize that its preferred filter has been discontinued.
Installation
Most filters come with detailed instructions on how to install them, according to Lewin, and they’re usually easy enough to install on your own. However, if your setup requires you to drill holes in your faucets or valves, Lewin recommends you get professional help—provided budget isn’t an issue.
Questions You Might Ask
What are the benefits of an under-sink water filter?
“There are several benefits of installing an under-sink water filter rather than using a pitcher filter or whole-house water filter,” insists Pinchev. Below are some of his top few:
They’re more convenient since you don’t need to keep refilling pitchers. They don’t take up valuable counter space, especially in small kitchens. The filtration is more targeted: It only purifies drinking water and doesn’t waste filtered water on washing dishes or showering. It affords better filtration than pitcher options, because under-sink water filters use water pressure (not gravity) to push water through the filter. The cartridge doesn’t need to be replaced as often as a pitcher filter might (e.g. six months minimum versus two months).
How do you install an under-sink water filter?
Each system can be different, but overall, there are some general guidelines for installing an under-sink water filter, according to Lewin. “If your sink doesn’t already have a spare faucet slot, you’ll need to drill one,” he says, reminding you to ensure that your water supply is turned off. “Once everything is prepared, locate your cold water pipe. Unscrew the pipe that connects the faucet to the cold water pipe, and connect the T-valve (usually included in the box) in the middle. Use Teflon tape around the threads on the connections to prevent leaks. Then, connect the plastic pipe and the shutoff valve (both usually in the box) to the T-valve.” Next, you’re ready to put together the faucet by following the steps in the manual, which Lewin says is usually the hardest part. Once that’s done, however, all you will have to do is mount the faucet on top of the sink.
How often do you need to change your under-sink water filter?
This will depend on the model you choose, but generally six months is the rule, says Lewin. Many options will also have auto-off functions or other indicators that will inform you when it’s time to change your filters, so you’ll never have to worry that you’re using an ineffective one. “I usually recommend people ignore the estimated lifespan length and focus on the number of gallons,” adds Lewin. “You can then estimate how often you’ll need to change the filter, based on your own family’s usage.”
Take Our Word for It
This article was written by Nikhita Mahtani, a freelance writer with six years’ experience writing and editing for home publications. To come up with this list, Nikhita researched the best under-sink water filters and consulted Gabe Pinchev, founder and CEO of FieldPulse, an online platform for service contractors, as well as Paul Lewin, a plumbing expert and founder of home maintenance blog Home Water Research.
