Operating Permit Fees

Counting multifamily dwelling units

Group A public water systems are required to report all service connections on their Water Facilities Inventory (WFI) every year. Some community water systems do not know how many actual dwelling units they serve.

A dwelling unit is a structure, or unit within a structure, with independent living facilities for one or more persons that include permanent provisions for living, sleeping, eating, cooking, and sanitation. A dwelling unit includes, but is not limited to, a single family residence or each unit of an apartment or multifamily building.

Even though some dwelling units may be served by a single master meter, we need to know the actual number of dwelling units served. You may be able to get accurate data about the number of dwelling units in a condominium, apartment, or other residential multifamily structure from one or more of the following sources:

  • The electrical utility usually bills each dwelling unit within a service area.
  • The sewer utility that serves multifamily buildings within your service area may use the number of dwelling units as the basis for their sewer charge.
  • Your residential customers with larger meters should be able to tell you how many dwelling units they serve.
  • The local planning office may track the number of dwelling units in approved multifamily developments.
  • The county assessor's office may maintain a database on the number of dwelling units in each multifamily development.

The bottom line is, you need to know how many dwelling units you're serving and report that number on the WFI. Every Group A community water system must use a credible process to estimate the actual number of dwelling units it serves.

Systems that serve larger numbers of households require more monitoring, planning and oversight to assure public health is protected. Problems in a larger system, although rare, can affect many people at once. Accurately counting dwelling units, residential service connections, and population is important to keep people in your community safe.

For more information, contact your regional WFI contact:

Eastern Regional Office: Sarita Preuss, 509-329-2166

Northwest Regional Office: Krista Chavez, 253-395-6772

Southwest Regional Office: Vacant