Intermittant sewage / Rotten Eggs smell from downstairs toilet - please help!

[helpingdan]

Hi all

I am new to the forum and really looking for some help - I am not a plumber nor an experienced DIY-er.

We moved into our new house a couple of weeks ago and a couple of nights in we noticed a bit of a stench in the hallway which was ultimately coming from the downstairs toilet. It smelt as if someone has been to the toilet and either not sprayed or flushed. The next morning the smell had gone, although the toilet still didnt smell great.

When we had a plumber come to fit a new gas hob for us he also checked out the toilet and he said he couldnt see any leaks or blockages but he definitely could get a whiff when he smelt down the back of the toilet towards the pipe that goes into the floor/wall. He said there was some gaps in the plasterboard/skirting boards and as a trial and elimination process to cover the holes with bags and tape it up.

After doing this the smell didnt appear that night but was back again the following night.

Someone else thought it may be the plastic piping with a seal in it at the back of the U-bend of the toilet and to try sealing that up, which we have done with silicone - still no difference.

The plumber came back again yesterday and sealed the front of the pipe that goes into the floor as thats where he reckons the smell is coming from and he said to pop off the skirting board and seal around the back of that pipe that he couldnt get to. I intend to do this over the weekend with the help of a carpenter I know. However, last night was the worst the smell has been.

At 8.30/9pm I came downstairs from putting my daughter to bed and no smell, by 10pm when I went back upstairs it stank in the downstairs toilet. The smell was gone by this morning.

I have taken up the lino flooring from the toilet as we are getting new ones in a couple of weeks to see if that is part of the problem. I have also checked the inspection chamber drain this morning - no blockages and when the toilet is flushed the water passes through the drain quickly and with no issues.

I am really hoping someone else has some other ideas? It is very annoying.

Sorry for the lengthy post.

Thanks

 

[glasgowplumber]

Difficult to tell without seeing pictures of how it's installed but your toilet waste stack may rise to about shoulder height and have an air admittance valve fitted, if it's faulty, fitted wrong or pretty old it can let smells out.

Is your upstairs toilet directly above the downstairs, or is it on the opposite end of the house?

 

[helpingdan]

Difficult to tell without seeing pictures of how it's installed but your toilet waste stack may rise to about shoulder height and have an air admittance valve fitted, if it's faulty, fitted wrong or pretty old it can let smells out.

Is your upstairs toilet directly above the downstairs, or is it on the opposite end of the house?

The upstairs toilet would be just about directly above, but also have an ensuite at the opposite end of the house. Neither of them smell.

But in relation to waste stack, air admittance valves etc I have no idea what you are talking about.

 

[RGII79]

change multiwik at back of the pan

 

[helpingdan]

change multiwik at back of the pan

Thanks, I reckon that is a job for a plumber rather than myself attempting it. I have a plumber coming round today to look at the issue and I will say this suggestion.

 

[glasgowplumber]

The water from your basin trap could be gettin drawn out when water is let go from the bathroom above, allowing the smell to come up.

again it's all guess work without seeing it but fitting an anti-syphon trap could solve it, always good to have one fitted anyway even if that isn't the route of the problem so nothing lost either way

 

[Mazp]

I agree with glasgow plumber,.As its an intermittent smell Its most likely your basin trap being sucked dry by the down flow from upstairs, then when basin is used again the trap fills up until the next flush from above.
If your wc pan connector was at fault you would more than likely have water leaking as well.
If there was a leaking waste under the floorboards, the smell would probably be constant.

 

[RGII79]

I agree with glasgow plumber,.As its an intermittent smell Its most likely your basin trap being sucked dry by the down flow from upstairs, then when basin is used again the trap fills up until the next flush from above.
If your wc pan connector was at fault you would more than likely have water leaking as well.
If there was a leaking waste under the floorboards, the smell would probably be constant.

Wax seal top of multiwik gone won't leak most of the time
has this smell always been ther or has it just started

 

[glasgowplumber]

Wax seal top of multiwik gone won't leak most of the time
has this smell always been ther or has it just started

They've just moved in, been doing it since they arrived according to OP

 

[Ermintrude]

Put Gaffa tape over overflow and plug hole in sink

 

[mike76]

Not vented properly! Stack should terminate above roof! If this is a problem to fix, vent directly to the toilet were smell is coming from!

 

[glasgowplumber]

Any update? Has the plumber been?