Implementation of the law for food retailers and distributors begins in January, with a longer phase-in period for schools, restaurants and several other large facilities.
Extreme drought now grips 85% of California, and meeting the reduction target could save enough water to supply 1.7 million average households for one year.
EBMUD declared a stage 1 drought in late April, meaning customers in Contra Costa and Alameda counties are being asked to cut water use by 10 percent, for now.