I am renting a house built in 1970's. We have a well and a RainSoft water system. I have a problem in the main bath room. Whenever someone is showering we get a smell like 'rotten eggs'. But it is not coming from the toilet, sink, or other house area like kitchen, washroom etc. Just in this one shower. It there a drain under the shower like a sink elbow that could be malfunctioning? Also it does intensify when we run the bathroom fan.

Most bad oders in bathroom drains come from rotting hair mixed with grease from the soap. Try this. Tonight before you go to bed pour 1/2 gallon of bleach down the shower drain and let it set overnight. Next morning flush it down with a few large pans of boiling water. The bleach will start to dissolve and soften the hair and make it slippery and the boiling water will melt the grease and flush the mess out into the main. Now see if that smelly drain doesn't smell sweeter? Hope this helps . Tom