It’s not an uncommon sight in large cities: smoke oozing from sewer drains in the streets as people walk by, undeterred. Some people may not think twice about the smog-like occurrence, but others might wonder why this happens. Does it indicate a problem in the sewer system? It actually can be just the opposite. A plumbing smoke test is actually a way to check for leaks in a sewer system.
What is It?
In a smoke test, a non-toxic, artificial smoke is pumped through the system in an effort to determine if there are any leaks. If there are any leaks in the system, plumes of smoke will form in these areas as they escape their confinement. This can be used to determine where sewer gas may be escaping from the pipes and potentially harming residents. This gas can sometimes have traces of the explosive methane gas or the deadly hydrogen sulfide gas. Although this test can be performed on a new building, it is usually reserved for buildings that have constant problems with the sewage system and suspect leaks might be the issue.
What is the Process?
When a city performs a smoke test on sewers there is a distinct process they often use as not to alarm residents. First they will identify the areas they need to test and then they will place notices on residents’ doors including the date they will perform the smoke test. Once they begin pumping in the smoke, they will look for smoke coming from the roof vents on homes, which shows the house is adequately connected to the sewer system. If smoke appears inside the home, however, this can indicate a leak somewhere in the system and people are advised to contact their plumber to perform further tests. Common defects range from broken caps to faulty oil rings on toilets.