DIY Doctor

Main navigation

New Bathroom - Intermittent Sewage Smell

Postby Lionelbl » Sun Aug 13, 2023 2:58 pm

Hi all,

First post here so please be patient.

We recently had our ensuite remodelled and were initially really happy with the result. However, there is now sometimes a smell of raw sewage which I have tracked to the back-to-wall toilet (it could have been the shower or the sink).

It's not always present and I can't discover what triggers it (whether it's another toilet in the house being flushed or something).

Anyway, I removed the front panel of the toilet unit and apart from the rubble which was left in the cavity, I was surprised to see that the contractor had used a flexi pipe which actually runs uphill from the toilet to the waste. I'm no expert but from where I'm sitting that doesn't seem like a good idea. Could this be the source of the smell?I wanted to attach some pictures to the post. Unfortunately, they're too big :(

Please give your honest opinions including how you would have solved the uphill waste issue (according to the specification, the toilet waste is 180mm from the floor, the main waste is higher but it's hard to say how much higher). Before I call the contractor back, I'd like some concrete facts to put in front of him.

Many thanks in advance!
Rank: Labourer
Progress to next rank:
Posts: 1
Joined: Sun Aug 13, 2023 2:00 pm

Postby stoneyboy » Tue Aug 15, 2023 8:29 pm

Hi lionelbl,
It is not good practice to have the invert level of the pan outlet lower than that of the waste connection, sadly it’s quite a common thing.
It is unlikely that this will cause sewage smells but if an air admittance valve has been fitted this is probably the source of the smell.
You could get the soil pipe work modified so the connection is lower or find a pan with a higher outlet. Neither solution will be cheap.
Regards S
Rank: Project Manager
Posts: 6315
Joined: Wed Dec 10, 2008 6:44 pm

Display posts from previous
Sort by
Order by

  • DIY How to Project Guides
  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!

  • Related Topics