No direct mechanical connection shall be made between the potable water supply and the swimming pool or spa, chlorinating equipment, or the system of piping for the swimming pool or spa, unless it is protected against backflow and back-siphonage.
Backwash water or drainage waters of a swimming pool or spa shall be discharged into a sanitary sewer through an approved air gap, or by other means approved by the District Government.
When necessary, filter backwash water and drainage water shall be treated chemically or through the use of settling tanks to eliminate or neutralize chemicals, diatomaceous earth, and contaminants in the water that exceeds the limits set by the District Government.
D.C. Mun. Regs. tit. 25, r. 25-C411