Two Systems, One Big Challenge
MSD serves the wastewater and stormwater needs of St. Louis City and 87% of St. Louis County. Much of this jurisdiction, including most of St. Louis County, is serviced by a separate sewer with two sets of pipes. Also known as sanitary sewers, wastewater pipes carry away the used water disposed of in sinks, dishwashers, showers, toilets, and floor drains in homes and businesses. Stormwater pipes collect the rainfall and snow melt runoff from yards, pavement, roads, and roofs and transports it to area waterways.
In the city of St. Louis and its adjacent suburbs, homes and businesses are served by a combined sewer system in which the pipes carry both wastewater and stormwater. Both dedicated wastewater and combined sewer pipes flow into one of seven water treatment plants, where the dirty water is cleaned and discharged into the area’s larger rivers.
Ideally, a wastewater sewer system need only have enough capacity to handle the sewage from its service area. But business and residential growth can create more wastewater than the original system was designed to carry. Sewers can also develop cracks that allow stormwater to leak into the pipes. The pipes can be overwhelmed with more wastewater than they were designed to handle, causing basement backups or the discharge of sewage into local streams.
When MSD first began operations in 1956, only about five percent of the population in the MSD service area received wastewater treatment. Today, MSD owns and operates seven wastewater treatment facilities treating an average flow of 350+ million gallons of wastewater per day. The Bissell Point and Lemay wastewater treatment plants are our two largest plants. Both serve the Mississippi River watershed. The Coldwater Creek and Missouri River wastewater treatment plants service the Missouri River watershed. The remaining treatment plants serve the Meramec River watershed.
Through our wastewater collection and treatment efforts, MSD keeps human and industrial waste out of our waterways, decreasing public exposure to pathogens and pollutants and provides critical wastewater management for our residential and commercial customers.
Take a Virtual Tour
Explore our Lower Meramec Wastewater Treatment Plant without leaving your chair. Tour the facility inside and out and get an up-close view of the critical services our treatment plants provide.