Some older sewer systems use a Combined Sewer System, which blends stormwater runoff with municipal sewage. Stormwater reaching the sewer system flows to a treatment plant and is treated along with sewage. There are serious risks with this system because combined sewers can handle only small rain events. Flash floods, which happen frequently in Texas, can quickly overwhelm this type of system, resulting in sanitary sewer overflows, which are messy, smelly and detrimental to lakes and streams. This can also be a health hazard since untreated sewage can transmit disease.
To prevent this, the City of McKinney, like most cities in North Texas, uses a Municipal Separate Storm Sewer System, which separates stormwater from sewage and conveys stormwater runoff directly to creeks and lakes. This type of system vastly cuts down the risk of sanitary sewer overflows and directs stormwater as efficiently as possible out of our streets and away from homes and buildings.
Learn more about separate storm sewer systems and why they are a better solution for stormwater than directing it to a treatment plant