D.C. Code § 34-2401.12
The water rates levied in the District of Columbia shall never be a source of revenue other than as a means of keeping up to said District a supply of water but shall constitute a fund exclusively for the maintenance, management, and repair of the system of water distribution.
R.S., D.C., § 198
July 12, 1876, 19 Stat. 87, ch. 180, § 18
Feb. 25, 1885, 23 Stat. 319, ch. 145
1973 Ed., § 43-1522.
1981 Ed., § 43-1531.