2025 Sanitary Sewer Smoke Testing

The City of St. Charles is conducting a program to identify locations where storm water is entering the City sanitary sewer system. The study, being performed by the engineering firm GHA Group, Inc. of Vernon Hills, Illinois, includes smoke testing of the sanitary sewers.

Smoke testing is a simple means of locating openings in the sewer system that allow surface rainwater runoff to enter the sanitary sewers. Air combined with non-toxic smoke is forced into the sewer at manholes, often located in the street, filling the system. Smoke will appear where there are defects in the main sewer line (usually located under the road) or laterals (connection between the main sewer line and a building) or where other connections to the sewer system exist, such as roof drains, patio drains and footing drains.

Smoke should not enter buildings unless there is defective plumbing or dried-up drain traps. Pour 1 gallon of water down all floor drains and any rarely used sinks/tubs/toilets to ensure that a water barrier is maintained in the drain traps. The drain trap water barrier prevents sewer gases or odors from entering the building. If the drain trap water barrier is present and smoke does enter your home, the potential exists for sewer gases to also enter your home and you should consult a licensed plumber to fix the problem. If smoke is entering your home during the smoke testing, you can contact the City of St. Charles Public Works Department at 630-377-4405.

The smoke is non-toxic, low odor, creates no fire hazard, leaves no residue, dissipates quickly, and is harmless. However, if someone in your home has respiratory concerns, they may wish to leave smoke-filled areas until smoke testing is completed. Please visit www.stcharlesil.gov for additional information on smoke testing. City of St. Charles staff will be happy to speak with you if you have any further questions about the smoke testing process or respiratory concerns.

Smoke testing is scheduled to begin during the first week in June and is expected to be completed by mid-October, weather permitting. Additional notification will be provided by door hanger cards prior to the start of smoke testing and signs will be posted when crews are testing in your area.

If you have any questions, please contact City of St. Charles Public Works at 630-377-4405.