D.C. Mun. Regs. tit. 25-B, § 1412
1412.1 A person shall not create a cross connection by connecting a pipe or conduit between the drinking water system and a nondrinking water system or a water system of unknown quality.
1412.2 The piping of a nondrinking water system shall be durably identified so that it is readily distinguishable from piping that carries drinking water.N
SOURCE: Final Rulemaking published at 56 DCR 5245 (July 3, 2009).