Cal. Code Regs. tit. 3, § 622
No cross-connections may be installed between a safe water supply and any unsafe or questionable water supply. Submerged inlets into an unsafe or questionable water supply must be avoided unless such submerged inlets are installed in a manner to prevent back siphonage.
1. New section filed 9-21-56; effective thirtieth day thereafter (Register 56, No. 18).