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Sewer Bypass/Overflow Incident Reporting

About Sanitary Sewer Overflows

A sanitary sewer system is a wastewater collection system that is specifically designed to collect and convey only sanitary wastewater (domestic sewage from homes, as well as industrial and commercial wastewater.) Storm water should be conveyed through a separate set of pipes that do not go to a wastewater treatment plant.

While all sanitary sewer systems collect a certain amount of stormwater and groundwater, some collect excessive amounts, so when wet weather conditions occur, capacity is exceeded and they may overflow. These overflow events are called sanitary sewer overflows (SSOs), and they are in violation of federal and state NPDES rules. In addition, unrelated to weather, line blockages or mechanical failures may prevent the system from operating properly, causing SSOs to occur. SSOs also include basement backups when sewage flows from a sanitary sewer back into a private lateral and then into a private residence. Basement backups caused by a blockage in a private lateral that prevents wastewater from leaving the home are not reportable SSOs.

When a system experiences an SSO event, the owner must report that event to the Indiana Department of Environmental Management within 24 hours. These report forms are to be submitted only by an authorized representative of the owner of the sewer or plant that overflowed, and are expected to an explanation of what happened and the name and signature of that person. Any time a bypass, overflow, basement backup, or SSO occurs, the responsible person should complete the form listed below on their computer and e-mail it to IDEM.

Treatment plant bypasses, which are releases of untreated or partially treated wastewater occurring at a wastewater treatment plant, must also be reported to IDEM within 24 hours using the same form.

For more information, contact the Office of Water Quality.

Forms and Reports

  • Bypass/Overflow Incident Report - State Form 48373 (available on the IDEM Agency Forms page)

Following is a listing of sanitary sewer overflow and wastewater treatment plant bypass events reported to IDEM. These lists may include some Combined Sewer Overflow (CSO) discharges occurring as dry weather overflows and other prohibited discharges. Normal precipitation related releases from authorized CSO outfalls are not included here. All lists are in alphabetical order by county.

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