Sanitary Sewer Smoke Testing

Purpose of Scheduled Sanitary Sewer Smoke Testing

Storm water entering the sanitary sewer system during heavy rainstorms could cause sewer backups. In addition, storm water entering our sanitary sewer that should be going to the storm sewer ends up costing all residents more money because the City pays Naperville for the treatment of that water that would otherwise be untreated. There are many ways in which rainwater enters the sanitary sewer system, including: directly – by connections from sump pumps, downspouts, and area drains (inflow) – and indirectly – by cracks and failures of the sewer pipes (infiltration).

To help identify the sources of rainwater inflow and infiltration (I/I), the City sometimes uses an investigation program using smoke testing of the sanitary sewer system.

About Smoke Testing

If Public Works staff will be performing smoke testing, residents in the immediate area of testing will be notified through front door hanger cards. City staff are uniformed, and operate out of vehicles marked with the City logo. Homeowners do not need to be home and staff will not enter residences.

Image of how smoke testing can identify defectsSmoke testing is a simple means of locating openings in the sewer system that allow surface rainwater runoff to enter the sanitary sewers. For the test, smoke blowers are placed on manholes and smoke is blown through the sewer system. Anywhere smoke exits, there is potential for storm water to enter the sewer system. Air combined with nontoxic smoke is forced into the sewer lines to disclose the location of connections and leaks. Smoke will appear where there are defects in the main sewer line or laterals (connection between the main line and a building) or where there are other connections to the sewer system such as roof drains, patio drains and footing drains.

Image of a drain trapThe smoke is nontoxic, dissipates quickly, and leaves no residue. The “smoke” is actually a mist containing a large percentage of atmospheric moisture that is highly visible at low concentrations.

Smoke should not enter a home or building if it is properly plumbed, vented and the water traps contain water. To help prevent smoke from entering your home, please pour water into seldom used sinks and floor drains. Pour one (1) gallon of water down any fixtures (sinks, tubs, toilets, showers, floor drains) that are seldom used to ensure that a water barrier is maintained in the drain traps and prevent smoke from entering your home. If smoke gets into your home, ventilate and notify the staff who are conducting the test outside your home/building.  

  1. Public Works