An important part of Charleston Water System's maintenance program is finding and fixing cracks, breaks, and other problems with sewer lines.
Our crews inspect pipes with robotic cameras and use smoke testing to locate cracks in pipes. Smoke testing involves using a device to inject a harmless smoke into sewer manholes, then watching to see where the smoke escapes.
It is normal for smoke to come out of sewer vent pipes on roofs of homes and buildings—this does not indicate a problem. However, if smoke emerges from storm drains or rises from lawns, sidewalks, or the street, that does indicate a problem, such as a cracked pipe, damaged manhole, or connection with a storm drain, etc. Our crews will note the the location and schedule appropriate repair.
Before conducting smoke testing, we notify the fire department and distribute door hangers to homes and businesses in the affected area.
Watch a video about smoke testing (1:43)
Crews mount a smoke blower on a manhole to begin smoke testing. The smoke is a nontoxic.
Smoke escaping from a storm water ditch indicates a problem that needs further investigation and repair.
What to expect during smoke testing
Smoke is supposed to escape through sewer vent pipes on roofs. These vent pipes are connected to your sewer plumbing to allow sewer gases to vent outside.
Occasionally, the harmless smoke will enter a home. This indicates there is a problem with the sewer plumbing in the home. If smoke enters the home, that means sewer gases are also entering the home. Contact a licensed plumber to make repairs.
During smoke testing of the sewer system, it's normal for smoke to escape from sewer vent pipes on roofs.
Why is smoke testing necessary?
The sewer system was designed to collect waste from homes and businesses—not rain water or ground water.
When rain or ground water enters the sewer system through cracked pipes, it takes up needed capacity in the sewer system, especially during heavy rain events. In severe cases, this can potentially cause sewer system overflows, which are an environmental and public health hazard.
To prevent this unwanted infiltration and inflow into the sewer system, we try to find and fix problems with sewer pipes and manholes that allow entry, such as root intrusion, deterioration of aging pipes, and mistaken connection of storm water pipes to sewer lines.
By systematically smoke testing our system, we have been able to remove an estimated 2.5 million gallons per day of extraneous flow for an annual cost savings of more than $400,000..
This photo of the inside of a sewer pipe shows a common problem—tree root intrusion. Inspection of sewer lines with robotic cameras and smoke testing allows CWS to find and fix these problems.