We just moved into our current house about a year ago (April 08). Last summer we noticed a sewage smell coming from the upstairs bathrooms. It was worst in the guest room bathroom, which we never used anyway. Over the winter, it seemed to go away so we did nothing. This summer, as the temperature has heated up outside, the smell has returned. We hired an exterminator to come out first because we thought it was a dead animal. $1500 later, and empty traps, the smell is stronger than ever. The guest room bathroom seems to be the culprit. We keep the door closed so it does not escape to the rest of the house, but it's almost as if the smell has gotten into the air ducts as it can be smelled in other rooms (albeit not as strong), especially when it's hot outside. We received a quote today to have our ducts cleaned for $1250, but they could not guarantee the smell would go away. I have no plumbing or ductwork experience, but it seems like the smell originates from the shower, then gets into the AC. Prior to our moving in, the previous owner did some bathroom renovation work by himself. Is it possible he created the problem? Where do I start to figure out what he could have done? I have read numerous threads about similar mysterious smells. I feel like there are a lot of unanswered questions still out there, and other solutions I don't fully follow. We had a plumber out today who could not figure it out. He was going to give us an estimate to come back with a pipe camera. To make matters worse, we have small children in the house--could the smell be toxic/harmful?

Thanks

Bathroom traps that aren't used often enough will evaporate to the point that the trap will not keep out sewer gas. Add water to the sink and shower/tub every other month. You could even add a cup of cooking oil and that will not evaporate. It could also be bad wax ring on the toilet. Fill the traps with water and then come back in a day or two and tell us if the smell is gone.

Thanks for the quick response. We have actually been using the bathroom/sink/toilet/shower for about 6 months now. The smell definitely seems to be coming from the shower/tub drain.

Could very well be rotting hair and body grease. I sometimes first use something called a Zipit to remove the hair. Then I mix 1/2 cup of baking soda with half cup of table salt, dump down the drain then add a cup of vinegar and watch the action. Nex day flush with big bucket of very hot water. Zip-It Unclog Drains in Seconds (http://www.zipitclean.com/)

Thanks for your post, however, no luck with the Zipit and salt/baking soda/vinegar. The Zipit did not retrieve anything. The drain seems to be clear. The Zipit was not easy to use though, as the drain only goes vertically down for a couple inches before shooting horizontal (Is this normal?). As such, it then took awhile to get the ingredients down. I did it gradually, and it seemed to be helpful. However, the next day the boiling water brought the smell back just as strong as before. Not sure where to go from here. The small is coming from this drain. The more time I spend in the bathroom, the more I am convinced the airducts have nothing to do with the root of the problem. My wife added today that she thinks the smell is definitely worse on hot, sunny days. Any thoughts are greatly appreciated. We will try anything--plumbers don't seem to have a solution.

Shower drains go down anywhere from 6" to 12" but then should go into a J shaped trap. Watch some of these clips http://www.wonderhowto.com/how-to-clean-shower-drain-trap/ Is this a tub/shower or a shower stall?

Thanks for your reply. I think we have a solution. Friday night we noticed a wet spot and crack in the garage ceiling (the nursery/guest room bathroom is overhead). The smell was unbearable, so Saturday morning we had an emergency plumber come out to check it out. Immediately upon walking into the bathroom he confirmed that we were smelling sewer gas. He cut into the ceiling and discovered there was no p-trap (?) ever installed. He sawed off the pipe and put a cap on it. (Can you tell I have no idea what I'm talking about?) The smell is gone. Amazing. The leak was pure luck, because we would have had to cut into the ceiling anyway to solve the problem (we probably would have spent even more money than we did trying different things until we lucked into the real culprit). Thanks for all your help.

BallengerB1,
Thanks for the help. I cannot figure out how to give you feedback--the site will only let me "rate" my own posts. You were extremely helpful. I appreciate your attempts, definitely very knowledgeable, and I'm very gracious you took the time to try.

THANK YOU BallengerB1!!

Not sure but I think you need at least 10 posts before they allow you to rate ny of us. Thanks