The Right Type of Valve
To control water flow and temperature, today's faucets use cartridge valves that enclose all the working parts in a single, easy-to-replace unit (meaning no washers to swap out). Some valves are made of plastic or metal, but the best ones house a pair of ultrahard, ultrasmooth ceramic discs that rarely leak and aren't affected by hard-water deposits. The only drawback: The discs are brittle and can crack if they snag any debris, so make sure to flush your supply lines before installing the faucet. Cartridge valves differ by faucet make and model; if you ever need to replace one, order it directly from the manufacturer.