Smoke testing is one of the most efficient and cost effective methods of locating sources of inflow and infiltration problems with sewers. The non-toxic "smoke" will help locate places where storm and other surface waters enter the sanitary sewers. It is conducted by placing a blower over a centrally located manhole and forcing non-toxic smoke-filled air through a sewer line. The smoke under pressure will fill the main line plus any connections, then follow the path of any leaks to the ground's surface, quickly revealing the source of inflow and infiltration. The smoke will be noticeable wherever there is a leak in a sanitary sewer pipe, such as a crack in a sewer pipe, a cross-connection between a storm sewer and a sanitary sewer, where a roof drain is connected to the sanitary sewer, from a broken cleanout cap, or from a defective or damaged manhole.
The smoke is specially manufactured for testing and is not dangerous or toxic, it leaves no residue or stains, and should not affect plants or pets. Visible smoke and/or smoke odor will last only a few minutes in cases of proper ventilation. The smoke has a very distinctive, but not unpleasant, odor. If traces of smoke or its odor are detected in buildings or homes, it is an indication that gases from the sewer system could also be entering. Sewer gases can be dangerous, and some of these gases have no odor or color, and can enter a building undetected. If smoke is observed inside a building during testing, corrective measures are strongly recommended.