Tap water in 700 Cypress and Stanton households was off-limits for drinking, cooking and bathing Monday after the local water supply was contaminated by a firefighting chemical.

Firefighters were using about 15 gallons of SILV-EX foam to extinguish a recycling center blaze Sunday afternoon in the 11200 block of Western Avenue in Stanton when a mixture of foam and water backed up into a fire hydrant, said Capt. Paul Hunter, spokesman for the Orange County Fire Authority.