Sewage in our Streams

Playing in water is a natural part of growing up, but if that water is contaminated, it can pose a health threat.

Many Indiana streams contain raw sewage from overflowing sewer systems, leaking septic systems or manure from animals. The bacteria count in these contaminated streams is often more than 100 times the national clean water standard. Sewage contamination of streams can introduce disease-causing pathogens into the water and threaten kids' health.


Combined sewers are sewer pipes that receive waste water from homes and businesses as well as storm water from storm drains along the streets. The combined waste water and storm water flows through the system to a wastewater treatment plant. When there is sufficient precipitation - in some cases as little as a tenth of an inch - the volume of water in these pipes is too much for the treatment plant, so the excess is released directly into streams at different points in the sewer system without being treated.

The law requires that all cities with combined sewer systems develop a Long Term Control Plan (LTCP) to eliminate, to the maximum extent possible, combined sewer overflows. Most Indiana CSO communities have submitted LTCPs that have been approved by IDEM while a few are awaiting approval. Click here to see dates of LTCP approvals.

Unfortunately, in past decades, as new homes and businesses were built, their wastewater was usually added to the system without building any additional capacity for wastewater treatment. Therefore, the increasing sizes of our communities has led to increases in sewer overflows. Since June 2007 Indiana has had a rule empowering the IDEM Commissioner to ban additional sewer connections to systems deemed to be at or near capacity.


Sanitary sewers are pipes carrying only waste water from businesses and homes. These pipes do not receive storm water. Overflows of untreated sewage from these systems happen when there are equipment failures or when too much storm water gets into the system from downspouts and sump pumps that are illegally hooked to the wastewater system. Untreated or partially treated sewage is sometimes released when a wastewater treatment plant exceeds its capacity. See IDEM's Sanitary Sewer Overflow Reports for Indiana.

CSOs and SSOs regularly occur in Indiana communities resulting in millions of gallons of raw or partially treated sewage entering streams and rivers. In some cases these streams are the source of drinking water for downstream communities.


Septic systems handle the wastewater on the same property where it is generated. The waste goes to an underground tank in which the solids settle and decompose. The residual liquid is allowed to trickle out into the surrounding soil from a tile field where remaining impurities decompose in the soil, however, much of the soil in the state is not suitable for septic tank operation (See Purdue website on Indiana Soils and Septics).

Septic systems can release bacteria and other contaminants into ground water or local streams. Garbage disposals in sinks have not been prohibited with septic systems; however, they can interfere with the function of a septic system by adding additional solids to the tank, often solids that do not decompose. See State Department of Health information on approved septic systems for Indiana. Permits for septic systems are handled by county health departments.