The maintenance, conducted on the Hetch Hetchy water system by the San Francisco Public Utilities Commission, may cause water turbidity. City officials say the water may have a milky appearance or a slightly different taste.
The water remains completely safe for drinking and other uses, but residents are advised to let the water sit for a few seconds to allow for the settling of air bubbles created in the transport process.
The maintenance began Tuesday and is scheduled to be finished in early January, according to city officials. The change in water quality is expected to last throughout most of the month of January.