The Western and Eastern Municipal Water Districts announced the reward Friday.
More than 60 fire hydrants have been stolen in the past several months, according to the departments, as well as backflow devices and manholes.
Water agency staff regularly provides information to scrap metal dealers, including recyclers and the Law Enforcement Joint Task Force, about water agency equipment and facility thefts, the departments said in a news release.
The districts are asking customers and residents to be vigilant to help prevent the thefts.
Area residents are asked to report any suspicious activity to local law enforcement by calling 911. If vandalism has already occurred to facilities, please contact the water agencies directly.
To reach the Western Municipal Water District, call (951) 789-5109. For the Eastern Municipal Water District, call (951) 928-3777, ext. 6265.