We have sewer smell inside our house in the basement in several places.

1. The water in the toilet in one of the not-so-often used bathroom in the basement would drain out after about a month. And then there will be sewer smell coming up. It would go away if we flush the toilet to let the water fill up again. But how to solve this problem in the long run? This bathroom is right next to the laundry room and the storage area that are described below.

2. The laundry room in the basement constantly have bad smell. There is a floor drain. There is the hole for the washer water pipe to go into. Then there is the big hole for dryer venting duct. We first had bad sewer smell coming up from the floor drain. The water in that drain looks stale and untouched no matter which toilet we flush in the house. It doesn't seem to connect with anyone. We plugged it with a red rubber plug and sealed it tightly. The smell from the drain definitely dramatically reduced. However it is still not completely odor free. We then entered into summer. The smell in the laundry room seem to go away for the most part even though once in a while it just doesn't smell fresh. But given there is no window or anything, we figured probably just not fresh air. Then winter comes again, we then smell strong sewer smell in the laundry room again. I think it comes from both the hole for the washer drain pipe and the dryer venting duct hole. I can't tell exact thought. But one strange thing is, the smell will significantly reduce if we run the dryer.

3. Next to the laundry room in the basement, is the small storage area underneath the stairs. That storage area has a whole on the wall we cut open due to suspicion of sewer pipe leak. Then we saw this vertical black PVC sewer pipe going up and at the bottom, there is a portion of it has a black rubber connection. We guess it is for allowing for movement. However, sniffing on that rubber, we smell sewer. We are not sure if it is supposed to smell through the rubber.

4. During the time we found the toilet smell, we also start to smell sewer at one particular spot on the wall in the master bedroom on main floor. I sniffed on the walls and it smells really bad. My husband cut a hole on the wall to see what's inside. We didn't see any sewer pipe adjacent. The smell definitely reduced a lot after we cut it open. However we don't know if it is because there were some smelly gas trapped there and now it is gone or it's just now the smell simply spread wide and you don't smell that concentrated on the wall at that spot any more. However, if we sniff carefully on that wall, there are still a stripe that has tiny bit of sewer smell. This area is almost directly above the smelly storage area in the basement.

5. Outside - outside of our house in the front courtyard and in between us and our neighbor's house, once in a while we smell sewer gas. The town utilities came out several times and been telling us there is no sewer lines going through and they have no idea why it smells. We haven't found a good pattern of when we smell it and when not. But overall we smell it a lot more often in winter than in the summer. And one thing we did find out is that the dirt underneath the surface dirt on our lot are those black organic top soil which smells just like sewer when we dig for planting and burying dripping systems. But many told us that over time the smell will go away. And we covered the entire ground by landscaping fabric and either rocks or grass or mulches. It is hard to imagine that lingering sewer smell is from the ground but we don't know for sure. And it is not everywhere. It only smells near the front courtyard and on the side between our houses and one spot in the back yard...

We had many plumbers and city inspectors stopped by. So far no one has really helped much. There is one plumbing company who suggested us to do a smoke test and would charge $1800 for it. I simply don't have the budget for it and not 100% confident whether that'll solve all the problems either. We need help. Please. Thank you so much!