D.C. Mun. Regs. tit. 25-C, § 6414
6414.1 The pool water shall be 0.5 or less NTU and the main drain grate shall be readily visible from the pool deck.
6414.2 Spa pools and swimming pools with heaters shall have a maximum water temperature of one hundred and four degrees Fahrenheit (104°F) (forty degrees Centigrade (40°C)).
SOURCE: Final Rulemaking published at 55 DCR 012845 (December 26, 2008).