Redmond has a hybrid water system. Depending on where you live, you may drink water from the Cascade Mountains or groundwater pumped from our shallow aquifer. Residents east of Lake Sammamish and the Sammamish River drink well water. During the summer, water from the Tolt Reservoir is blended with the well water to help meet peak summer demand.
Redmond's drinking water aquifer is an underground body of groundwater that is stored in spaces between sand and gravel. Supply wells pump groundwater from the shallow aquifer that resides beneath the downtown area and the Bear Creek and Evans Creek valleys.
Recharge to a shallow aquifer.
Groundwater moves with gravity through the spaces within the soil. Soils control groundwater's movement, where it enters (recharges) the aquifer and where it leaves (discharges). Redmond's aquifer is mostly recharged by precipitation when rain water infiltrates through the soil and reaches the water table. The water table is the top of the saturated zone of sand and gravel. The water table fluctuates with precipitation, reflecting seasonal precipitation patterns. Groundwater discharges occur in areas such as streams, springs and lakes where the water table is intercepted by the land surface. Wells also discharge groundwater through pumping.
Water from the Evans Creek area near HWY 202 recharges the aquifer.
Reliable and high-quality drinking water is important to our community. Redmond is committed to protecting our water supply, maintaining the City's water system, and planning for future years of service. It is far less expensive to prevent pollution that could contaminate groundwater because contaminated groundwater can be very expensive to clean up. The cleanup process lasts decades, causes supply wells to be shut down for years, and adds expensive treatment at wells.