D.C. Mun. Regs. tit. 25, r. 25-G404
All handwashing sinks, including those in toilet rooms, shall be equipped to provide water at a temperature of at least one hundred degrees Fahrenheit (100 °F) (thirty-eight degrees Celsius (38 °C)) through a mixing valve, a combination faucet, or tempered water and a single faucet.
A steam mixing valve shall not be used at a handwashing sink.
A self-closing, slow-closing, or metering faucet shall provide a flow of water for at least fifteen (15) seconds without the need to reactivate the faucet.
Any automatic handwashing facility shall be installed in accordance with the manufacturer's instructions.
At least one (1) handwashing sink is required at a workstation. However, for every four (4) workstations, beyond the first workstation, an additional handwashing sink is also required. All handwashing sinks shall be conveniently located and used exclusively by body piercers or tattoo artists for washing their hands and preparing their clients for body piercing or tattooing. Use of the handwashing sink in the toilet area identified in Subsection 505.2 is prohibited for this purpose.
D.C. Mun. Regs. tit. 25, r. 25-G404