D.C. Mun. Regs. tit. 14 § 606
Each residential building shall be provided with a water heating facility which is properly connected with the hot water lines of the required fixtures, and which is capable of providing sufficient hot water at a temperature of not less than one hundred twenty degrees Fahrenheit (120° F.) at those fixtures to meet normal demands.
Where the hot water heating facility is not under the control of the occupant of any habitation, the owner or licensee of that residential building shall provide and maintain a continuous supply of running hot water to meet normal needs.
The owner of a single-family dwelling, occupied in whole or in part by a tenant or tenants in which one (1) or more housing violation notices were issued because of a defective water heating facility, under the control of the owner, and whose water heating facility is separate from the central heating system, shall cause the water heating facility to be inspected by a qualified person in the period between March 1 and September 1, subsequent to the issuance of the violation notices.
In addition to testing the efficiency of the water heating facility, the flues, vents and dampers shall be inspected for escape of carbon monoxide gas.
The findings on inspection shall be recorded on forms approved by the Department of Consumer and Regulatory Affairs ("Department") within fifteen (15) days following the inspection and shall be delivered to the owner, who shall file a copy with the Department within seven (7) days of receipt of the findings.
The owner shall correct all defects as found upon the inspection before October 1 of that year and shall certify to the Department that the corrections have been made.
The owner of a multiple dwelling containing two (2) or more units, whose water heating facility is separate from the central heating system, shall cause the water heating facility to be inspected by a qualified person between March 1 and September 1 of each year.
Pursuant to § 606.7, in addition to testing the efficiency of the water heating facility, the valves, vents and dampers shall be inspected for escape of carbon monoxide gas.
Pursuant to § 606.7, the findings on inspection shall be recorded on forms approved by the Department of Consumer and Regulatory Affairs within fifteen (15) days following the inspection and shall be delivered to the owner, who shall correct all defects as found upon the inspection before October 1 of each year, and shall certify to the Department that the corrections have been made.
For the purposes of §§ 606.3 through 606.9 and 606.11, the term "qualified person" means a master plumber and gas fitter, heater and air conditioning contractor, master mechanic, licensed by the District of Columbia, or a certified employee of a public utility.
The certifications required by §§ 606.3 through 606.9 shall be in writing and shall be signed by the owner and by a qualified person.
D.C. Mun. Regs. Tit. 14, § 606