Water leaks can sometimes be a difficult to find, but locating a leaking odor can be even more challenging. Common causes of sewer odor can result from broken fittings, nail holes in pipes, or toilets leaking at their wax seals. Our first step is to check the basic or more obvious places sewer odor can escape. If no leak is found with the H2S sensor equipment, a non toxic smoke test is used to track the leak back to the source.