You must make sure that systems delivering not-fit-for-drinking (nonpotable) water prevent backflow into drinking water systems.
Wash. Admin. Code § 296-800-23015
Statutory Authority: RCW 49.17.010, [49.17].040, and[49.17].050 . 01-11-038, § 296-800-23015, filed 5/9/01, effective 9/1/01.