The Sewickley Water Authority system begins with three quality groundwater sources in the area. The sources consist of two wells and one crib intake. The water from these sources is pumped into our plant were the water begins the treatment process through a series of steps. To begin, the raw water is sent to an aeration tank, which allows for oxidation of the high iron levels that are present in the water. The water then goes to a mixing tank where polyaluminumchloride and sodium hydroxide are added. The addition of these substances cause small particles to adhere to one another (called "floc") making them heavy enough to settle into a basin from which sediment is removed. Chlorine is then added for disinfection. At this point, the water is filtered through layers of fine coal and silicate sand. As smaller, suspended particles are removed, turbidity disappears and clear water emerges.
Chlorine is added again as a precaution against any bacteria that may still be present. (We carefully monitor the amount of chlorine, adding the lowest quantity necessary to protect the safety of your water without compromising taste.) Finally, sodium hydroxide (used to adjust the final pH and alkalinity), fluoride (used to prevent tooth decay) and a corrosion inhibitor (used to protect distribution system pipes) are added before the water is pumped to our water storage facilities.
From there, the water is pumped to our Water Works Park storage tanks. From the storage tanks the water is then fed to two separate systems. The lower elevations of the system (Sewickley, Glen Osborne, Haysville, and Edgeworth) are fed from the tanks by gravity, while the upper elevations of the system (Sewickley Heights and Aleppo) are fed through a pumping station.
The Sewickley Water Authority system also includes a distribution system that is comprised of 40 miles of main lines, 1,200 isolation valves, and 300 fire hydrants. The Sewickley Water Authority system serves approximately 2,200 customers through metered connections.