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.

Start with our under sink reverse osmosis system guide. It explains how the stages work, tank vs. tankless designs, NSF/ANSI 58 certification, costs, and how to keep membranes and filters in good shape.

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Under Sink Reverse Osmosis System: Costs, Stages & Buying Checks