I've just moved into a newly build house a few months ago and every time it rains, it smells like sewer in a bathroom and the living room.

I'm using the municipal sewer and I checked in my own yard to make sure it's not clogged and everything is fine.

I don't know what to do and I've had one plumber come to check it out, but he couldn't find any reason.

What else should I look for? I can give you more details, but I need to know what exactly.

  • I think you need to track down where exactly the smell is coming from. Places to check first: Sump Pit, floor drains, shower drain in the basement. Is there a chance that the rain gutters in the home were incorrectly attached to the city sewer? A home I was going to purchase failed inspection partially due to having the rain gutters / sump pump attached to the sewer system.
    – cyclops
    Jan 17, 2018 at 18:56
  • The rain from the roof goes into the sewer system. It first goes to some kind of well that has a pump triggered by a sensor. This is because the back of the house is below the sewer's level. Floor drains seem to be ok, I keep pouring water in them to keep them wet, because I think my underfloor heating might dry them. Jan 17, 2018 at 19:26
  • Where I live water from the roof goes into the surface drainage which does not go into the "sanitary" sewer system. The surface drainage goes into creeks and from there into lakes and rivers. Jan 17, 2018 at 19:39

1 Answer 1


Well normally all plumbing has a TRAP - there are a couple reasons for this - the P-TRAP fills with water and provides a barrier between the inside of the house and the outside of the house. This can prevent critters from entering (not completely but less likely), it also prevents sewer gases from entering into your home. Since yours happens to be when it is raining the sewer systems are loaded with additional water - and perhaps based on how that system is - your house is unduly affected. That said I would be investigating your plumbing for the proper installation of TRAPS.

You stated in a Bathroom and also in a living room. Where is this living room in proximity to that bathroom or other drains in the house ?

I suspect you have a missing TRAP somewhere or a blocked Vent Stack - and most probably related to that specific bathroom. Your plumber should run a camera down the drains in that bathroom and the Toilet itself, and also the VENT Stack for that bathroom - plumber should check for clogs of the vent stack or a covering - as when it rains is your vent stack becoming blocked.

Seeing as it is new construction sometimes things are blocked off during construction or debris can fall into it thereby creating a blockage. Have the plumber check it thoroughly with a camera system - snake the thing does not tell you much unless you run into something. The camera will spill the beans.

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