Method for Billing Certain Multi-Unit Properties

Historically, WSSC has billed multi-unit residential properties such as apartment buildings using a “unit count” method. This particular billing method provided consistency with the way single family residential properties were billed. The unit count status allows us to divide total gallons by the number of units at a particular property. This lowers the Average Daily Consumption (ADC), which in turn, lowers the billing rate based on the ADC in gallons. 

Because there has been a trend towards building mixed use multi-unit properties that contain a majority of residential units as well as one or more commercial units, we adopted Standard Procedure (SP CUS 11-01, effective December 31, 2011), which specifically addresses how WSSC will bill “mixed use” multi-unit and “multi-unit residential” properties.

If WSSC did not receive your completed “Billing of Certain Multi-Unit, Mixed Use Accounts” questionnaire prior to April 1, 2012, your Unit Count status has been canceled. To obtain the required postcard, please contact Ms. Shantel Porter at 301-206-8840 or

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