Upon arrival, the customer reported a persistent sewer-gas odor in both the downstairs bathroom and the upstairs bathroom directly above it. They also expressed concern about a possible break in the sewer line. I explained the potential causes of sewer odors and began by running a camera inspection on the downstairs sewer line to check for bellies, breaks, or other abnormalities. Approximately 5 feet from the stack, I found a section of pipe holding water, indicating a slight belly. There was also minor root intrusion at the tap, but neither issue was significant enough to allow sewer gas into the home. The exterior sewer line was inspected as well and was found to be in good overall condition. Next, I inspected the downstairs bathroom where the odor was strongest. Upon opening the shower door, I discovered a large number of dead sewer flies. The shower trap was completely dried out, which will allow sewer gases to enter the home and can also attract sewer flies. I filled the trap with