Reverse Osmosis

Under-sink reverse osmosis system with filter stages, membrane and storage tank below a sink with a drinking faucet

Reverse osmosis (RO) pushes water through a very fine membrane. According to the CDC, RO filters can remove germs and some chemicals, including lead, copper, and sodium, and may reduce arsenic, fluoride, and nitrate. Most homes install RO under the kitchen sink for drinking water.

Our RO guides cover costs, tank vs. tankless designs, whole-house RO, and how to keep membranes and filters in good shape.