Best Under-Sink Water Filters of 2025

Under-sink reverse osmosis water filters are recommended if your water contains a wide range of contaminants or bacteria. (To find out, check the water-quality report issued annually by your water supplier, or if you have a well, have your water tested.) 

Reverse osmosis filters remove water contaminants like lead, volatile organic compounds (VOCs), PFAS, arsenic, bacteria, and viruses, according to the Environmental Protection Agency. Reverse-osmosis filters force water through a semi-permeable membrane, separating it into filtered, drinkable water and contaminated “reject water.” So although these systems improve water quality, they also generate a lot of wastewater—as much as 5 gallons for every gallon of filtered water, the EPA says.

For lead, chlorine, and other contaminants, standard under-sink filters that meet NSF/ANSI certification should do the trick. (NSF International and the American National Standards Institute develop water filtration standards.) All under-sink water filters in CR’s ratings are certified to the NSF standard for removing lead and chlorine.