While trace levels of lead are sometimes detected, all samples to date have been in compliance with the standards established by the Washington State Department of Health and the Environmental Protection Agency. Lead and other metals are more readily leached from plumbing and fixtures by hot water. Therefore, it is always recommended to heat cold water for making baby formula, coffee, tea and other cooking purposes, rather than using hot tap water. To check the valve, turn off the cold water underneath the sink and turn on the cold water at the faucet. If water comes out of the faucet, the mixing valve is worn and should be replaced.
Cold water can also leach metals while standing in pipes.
It is recommended that the cold water in a faucet that has not been used for six or more hours be run for about five seconds before use for drinking or cooking. This will flush out any metals that may have accumulated in the standing water. Several inquiries have arisen recently due the installation of stickers on fume hoods warning against the use of perchloric and hydrofluoric acids. Perchloric acid is a strong oxidizer, which when volatilized in a fume hood may precipitate on ductwork surfaces. Literature references cite cases where incidents have occurred in ductwork serving hoods in which perchloric acid had been used.