D.C. Mun. Regs. tit. 21, r. 21-102
No public watermain shall be tapped or connections made to a public watermain under any circumstances, except by the regular tappers or construction forces of the Department.
The provision of taps or connections to the public watermain shall be at the expense of the applicant.
Upon application, approval, deposit of cost by the applicant, and the submission of an executed "Authority Card" for each service, the Department will install taps (sizes 3/4 in. through 2 in.), or connections (3 in. in diameter and larger) including tees, sleeves, valves, valve casings, or valve boxes.
Each water service larger than one and one-half inch (11/2 in.) shall have stop valve with approved valvebox as close as practicable to the public water main.
Taps or connections to watermains larger than twelve inches (12 in.) in diameter will not be permitted with-out specific written approval of the Director or his or her duly authorized representative.
No tap or connection shall be nearer than two feet (2 ft.) to a bell or coupling of a watermain.
No two (2) taps shall be nearer together than two feet (2 ft.).
In no case shall a water service pipe from the tap in the main to the building line be less than three-quarters of an inch (3/4 in.) in size.
In no case shall the valves of the service pipe be smaller in size than the supply pipe.
D.C. Mun. Regs. tit. 21, r. 21-102