D.C. Code § 8-105.08
In order to determine compliance with this subchapter or any rule issued pursuant to this subchapter, WASA, a WASA authorized representative, and the Mayor shall have a right to enter upon or through any premises subject to this subchapter at reasonable times for the purpose of inspection, observation, measurement, sampling, and testing. The right to enter and inspect shall include the right to copy records related to compliance with this subchapter. Where a user has security measures in force which would require proper identification and clearance before entry, the user shall make necessary security arrangements so that, upon presentation of suitable identification, the Mayor or WASA will be permitted entry without delay.
D.C. Code § 8-105.08