A faint sewer odor started a few months ago, coming from our master shower. The odor was noticeable after showers but gradually went away as the day went on. Now the odor has gotten considerably stronger. There is no clog – the water runs fine. We have tried using drain products, bleach overnight, and we have snaked the drain but the odor still persists. The only change that happened a few months ago was that our neighbor started building an in-ground pool.

The pool is not a likely contributor to your issue. You need to inspect your vent pipe that goes out through your roof. It is possible that it is cracked or a connection has opened. This would be a place to start if this is swer gas, are you fairly certain it is sweer gas or is it just a bad odor?