Frequently Asked Questions

The Sewer Division has performed hundreds of sewer system evaluations. Smoke Testing is one technique utilized to identify sections of sewers which may exhibit inflow during heavy rainfall.
Smoke Testing is best used to detect inflow sources such as:
- Roof Leaders
- Cellar
- Yard and Area Drains
- Foundation Drains
- Abandoned Building Sewers
- Faulty Connections
- Illegal Connections
- Storm Water Drainage System Cross Connections

It can also detect structural damages and leaking joints in sewer pipes and overflow points in sewer systems.

A 2-man or 3-man crew from the Sewer Division will use a high capacity blower smoke technique to test each sewer line. Smoke blowers are placed on manholes and smoke is blown through the sewer system. Anywhere the smoke exits, there is potential for stormwater to enter the sewer system.

Prior to beginning the smoke testing, the Sewer Division will place door hangers on the front door of every building on the streets to be smoke tested at least 24 to 48 hours in advance. Notices will be distributed by 2 people from the smoke testing field crew. If requested by the city, the Sewer Division will post the smoke testing schedule on the

The Sewer Division’s personnel are uniformed and carry identification badges. Crew members operate from vehicles with Village of Deerfield signage.

No. The smoke that comes out of the vent stacks on houses or holes in the ground is non-toxic, harmless, and has no odor. It does not create a fire hazard.

Drain traps should always be filled with water to prevent sewer gases from entering the building. About 3 cups of water should be poured in floor and sink drains, filling the traps to prevent smoke from entering the home. If smoke does enter, the resident should consult a licensed plumber. If harmless smoke can enter through faulty plumbing, the potential exists for dangerous sewer gases to also enter the home. Should smoke enter your building or structure, contact a member of the smoke testing crew working in the area.

This could mean that there a drain on the property which is connected to the house lateral instead of the storm system. It could also mean that there is not direct connection, but that the lateral has breaks or cracks in the pipe that drain runoff after it has percolated into the soil.

In a worst-case scenario, yes, but there are many other solutions, such as disconnecting the drain or lining a portion of the house lateral without an excavation.

Homeowners do not need to be home and at no time will field crews need to enter the residence. Field inspectors will be noticeable documenting the testing, taking photos and measuring distances so that the defects may be found at a later date and repaired.

Obviously, if the sanitary sewer line and the lateral are in good condition, and there are no drainage facilities connected to them, the smoke has no place to go other than up the house vent stack, as it is supposed to. However, sometimes the smoke doesn't appear at all even though there is a defect. The Sewer Division crews are trained to identify these "suspect" situations and performed a dye test to conclusively determine whether the suspect is positive or negative. But this is a subject for its own set of QAs.