A key feature of California’s drinking water system is the large number of individual water systems.

There are approximately 3,000 Community Water Systems (CWSs) in the state, meaning systems that serve a residential population year-round (the remaining 5,000 of the state’s 8,000 Public Water Systems are non-community systems serve places like schools, daycare, hospitals, campgrounds, or businesses that serve at least 25 people but have transient or non-residential populations.