A county sanitation district may acquire, construct and operate sewage collection, treatment and disposal works within or outside district boundaries. It may also provide water services.

A district may include incorporated or unincorporated territory. The governing body of a county sanitation district within unincorporated territory only is the board of supervisors. The governing board of a county sanitation district which includes both incorporated and unincorporated territory is made up of both city council and county supervisor members depending on the amount of overlap.