Wastewater from homes and businesses is conveyed to the main sewer line, which transports sewage to a force main, which is used to move wastewater up the hill to the wastewater reclamation facility for treatment.

Pump stations move wastewater along the system. In the Belfair wastewater system, three pump stations are being designed to direct wastewater toward the treatment plant.

Mason County will be employing a new, proven technology for the Belfair Wastewater and Water Reclamation Facility (treatment plant) called a membrane bioreactor (MBR) system. This treatment technology uses biological processes and microfilters to achieve very high quality water, which can be reused.

Mason County is employing a strategy of a “decentralized” wastewater treatment system. Mason County Commissioners recognized early on in 2006 that this wastewater treatment system needed to be decentralized to allow for effective water reuse. Mason County recognizes that water reuse is a component of responsible environmental stewardship. This means that the County is committing to building smaller treatment facilities in logical places where they are needed, which will enable the highest and most efficient use of the County's water resources.

The Belfair Water Reclamation facility will produce “Class A” reused water. Class A water is being used all over the world. In Washington State, reused water is suitable for irrigation, industrial process, stream augmentation, and other beneficial uses.