One of the most common complaints we received at the city where I used to work was sewer odors in homes or businesses. The callers always assumed it had to be caused by the city sewers, and therefore, they always requested that we flush our lines to solve the problem. So the city had adopted the practice of responding to these calls by flushing the sewer in front of the home or business of the caller. It always frustrated me because of course our sewers smelled and flushing them was not going to permanently solve the person’s problem. But unfortunately it was difficult to get people to accept the fact that if they have a sewer smell it’s most likely due to a problem with their plumbing.
Finding the real solution to the problem
Occasionally some people would call back after we cleaned our sewer because of course the problem did not go away. So because at this point they were more willing to accept that it might be a problem in their own building, we were able to work with them to help discover the source of their problem. In most cases it was either a vent that had developed cracks or holes or was blocked. In one case we found the sewer for the business had broken underground in front of the building. We realized this because we had gone into the basement of the neighboring business and saw sewage seeping in and running down one of their walls. If you’re interested in other causes of sewer odors, there’s a great write-up by the askthebuilder site: “Sewer Gas Smell.” The post also discusses methods of finding and solving the problem. One additional tip I didn’t see on that site was to put a small amount of vegetable oil in floor drains that are infrequently used (just enough to cover the water surface because normally putting oil in sewers is a very bad idea). This helps prevent the water from evaporating. There are a few more good tips at getting rid of sewer smells at this link in the Tips Bulletin: “How to Get Rid of Sewer Smell in Your House.”
When cleaning the city sewer does help
Although cleaning city sewers does not help eliminate sewer odors in a home or business, it can help minimize odors that are experienced along a street in communities with combined sewers. These sewers convey both sewage and rain water so the inlets and catch basins along the street are directly connected to the city’s sanitary sewers. And because of this, sewer gas is sometimes vented out of the sewer through these basins. Where I worked, the city still had some areas with combined sewers. And at some of these locations, the smell along the street seemed to get worse during times of low flow or no rain. So we found we could minimize the smell by flushing water into the sewer. However, we had at least one area with high sewer flows that would continually vent through the basins. Finally in this location we had to replace the basins with ones that had traps to prevent the smell from leaving the sewer.
So if you’re experiencing sewer gas odors in your home, it’s best to follow the advice found on the askthebuilder site and call a plumber rather than the city. However if you have no smell in your home, but notice an odor out along the road, particularly near an inlet, then it’s best to call the city or utility company.