The Metropolitan Domestic Water Improvement District (District) was formed in July 1992 when its residents successfully petitioned the Pima County Board of Supervisors to form a domestic water improvement district in order to have an independent and direct voice in water issues rather than be a part of Tucson Water without voting rights. A five-member elected Board of Directors, from within its boundaries, governs the District. The District has 22,072 active accounts and six-service areas.
- The Metro Main service area is the District’s original service area and covers approximately 26 square miles in the northwest metropolitan Tucson area. Metro Main’s storage facilities include the Herb Johnson Reservoir (5 million gallons), the James M. Tripp Reservoir (5 million gallons) and the Magee/La Cholla Reservoir (1 million gallons).
- In 1999, the District acquired the Metro Hub Service area and annexed this area in 2003.
- In December 2009, the District acquired the Thim Water Systems, located southwest of Tucson. These systems are part of the Metro Water service area and includes Metro Southwest – Diablo Village, Metro Southwest – E&T, and Metro Southwest – Lazy B. These areas have not been annexed into the District’s legal boundaries.
- The District includes Arboles Viejos known as Metro West as a service area that was annexed into the District in 2005. This is a 619-acre planned development area with no current services.
The total water storage capacity is 13.6 million gallons in the Metro Main service area, 1.05 million gallons in the Metro Hub service area, and 747,000 gallons in the Metro Southwest service areas.