Smoke Testing: The Answer to Sewer Main Overflow

When stormwater enters a sewer system through a pipe defect, loose connection or a manhole, the system can become overburdened and may ultimately overflow. Sanitary sewer overflow is a serious and even dangerous scenario that can be costly and disruptive to remedy. Municipalities use multiple methods to prevent overflow, including using dyes, pressure testing or smoke testing to detect possible leaks. This discussion of smoke testing may help you determine whether it is the right method for your needs.

What Smoke Testing Does

A sewer smoke test is a reliable way to detect breaches in sewer main lines. Yard or foundation drains, faulty connections and abandoned sewers are points where unwanted stormwater can enter a sewer system. Because this can overburden the overall system and the sewage treatment plant, it is important to have a reliable testing method to identify breaches. 

How Smoke Testing Works

The sewer section to be tested will be blocked off to isolate the target area. A three to five-person crew will place a smoke blower over a manhole and blow thick smoke into the sewer system. The crew will spread out along the tested area to monitor the results. Smoke testing uses a non-toxic, odorless smoke that is easily visible even in small amounts. A sewer in good condition will generally reveal smoke coming from only manhole covers and roof vents. If defects exist, the smoke will be detected escaping from breaches in the system. It’s not unusual to see test smoke coming from cracks in streets or backyards. Technicians will mark or flag any breaches, and the results will inform necessary system repairs.

Smoke testing has become the preferred standard for identifying leaks in sanitary sewer lines. It is a non-invasive, non-toxic and reliable method for identifying small defects that could turn into big problems. If you see white smoke coming from a crack in your street, it’s quite possible there is a smoke test happening in your area.

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