Leo Nelson Riverside Water Treatment Plant

Primary Softening Basin 


On April 29, 1997, the Water Department broke ground on its $17.5 million expansion of the Riverside Water Treatment Plant. This expansion doubles the plant's capacity to 32 million gallons of water a day.


Approximately 94% of Elgin's raw water is from the Fox River with the remaining 6% drawn from deep wells. The water is treated and tested per the Environmental Protection Agency regulations. The raw water undergoes a tertiary treatment process, including coagulation / sedimentation, lime softening, chlorination, and filtration.

Raw Water Facts

The raw river water has a hardness of 260 to 400 milligrams per liter (15 to 24 grains per gallon) and is softened to 135 mg/L (7.9 grains per gallon). There is a total combined chlorine residual of 3.0 mg/L for disinfection. Fluoride is mandated and added for the prevention of tooth decay.