Sewer smells

[Hen3ry]

Hi,

We have a five storey block of flats built in 2006 and are experiencing sewer smells in some of the bathrooms, mainly on the first and second floors. The soil stack is vented to the atmosphere and has a mesh cover. It appears to be clear of blockages as far as can be seen with a torch from the top.

The smells are mainly from the baths which have shallow traps and from shower bases. The water in the toilet bowls drops by up to an inch overnight. Air can also be heard in the traps on the third floor.

As with many new builds, all the plumbing is enclosed without access points in the bathrooms so it is difficult to find a resident willing to have their bathroom demolished to investigate the problem!

The developer claims that he has no plans of the plumbing as it was sub-contracted.

A couple of plumbers have investigated but not come up with any suggestions.

Any advice would be most welcome.

 

[nadia69]

Hi,

We have a five storey block of flats built in 2006 and are experiencing sewer smells in some of the bathrooms, mainly on the first and second floors. The soil stack is vented to the atmosphere and has a mesh cover. It appears to be clear of blockages as far as can be seen with a torch from the top.

The smells are mainly from the baths which have shallow traps and from shower bases. The water in the toilet bowls drops by up to an inch overnight. Air can also be heard in the traps on the third floor.

As with many new builds, all the plumbing is enclosed without access points in the bathrooms so it is difficult to find a resident willing to have their bathroom demolished to investigate the problem!

The developer claims that he has no plans of the plumbing as it was sub-contracted.

A couple of plumbers have investigated but not come up with any suggestions.

Any advice would be most welcome.

sounds like a blocked drain if the toilet bowl water drops , lift the manhole covers and have a look

 

[Reg Man]

Sounds like a soil stack design problem. Traps on the baths and showers siphoning out. No easy solution, without seeing the building. Can fit anti-siphon traps but this may not be practical.

 

[Ermintrude]

Is it in a windy location? My old house was on a high ( snow in August - consett) hill and four floors , wind used to suck water out of traps.

 

[Hen3ry]

Sounds like a soil stack design problem. Traps on the baths and showers siphoning out. No easy solution, without seeing the building. Can fit anti-siphon traps but this may not be practical.

Have installed hepvo valve on one bath but this has made the problem worse on the next floor. I don't understand how you get syphoning on an open stack, standard sized to current building regs.
If there was a blockage, then sewage would back up.

It can be a windy location but the problem appears to be there in all conditions.

 

[Ermintrude]

Defo design issue but no use proposing needs to be looked at.

Might be plug from top floor causing pressure wave as it comes down stack.

 

[Hen3ry]

Thanks - back to the drawing board then.

 

[Reg Man]

Have installed hepvo valve on one bath but this has made the problem worse on the next floor. I don't understand how you get syphoning on an open stack, standard sized to current building regs.
If there was a blockage, then sewage would back up.

It can be a windy location but the problem appears to be there in all conditions.

We obviously can't see the soil stack design, so its difficult to give you the answer. I am convinced there is a design issue. So If I direct you towards Building Regulations Document H pages 8 to 10, this will give you an idea if your system complies. This document is downloadable from the DCLG government web site and is free.

 

[solutions]

Have installed hepvo valve on one bath but this has made the problem worse on the next floor. I don't understand how you get syphoning on an open stack, standard sized to current building regs.
If there was a blockage, then sewage would back up.

It can be a windy location but the problem appears to be there in all conditions.

Hydraulic jump can do strange things. As there is no way of knowing if your services plumb straight in to stack or are combined before entering stack or if each flat is plumbed same way, Too many variables to propose a definitive solution. If you want it fixed for your flat fit anti syphon traps or hepvo s on all affected outlets.

 

[solutions]

Its a shame in some respects that we dont do here as they still do in US and plumb a seperate vent only link to all wastes or in some cases a completely vent only stack.

 

[Reg Man]

Its a shame in some respects that we dont do here as they still do in US and plumb a seperate vent only link to all wastes or in some cases a completely vent only stack.

That is exactly what we used to do here in the UK, but it seems that labour and material costs and what we think we can get away with, has taken over and we get problems now.

 

[solutions]

That is exactly what we used to do here in the UK, but it seems that labour and material costs and what we think we can get away with, has taken over and we get problems now.

Yes have seen it in older text books etc I can understand for most installs the requirment probably isnt there but this sort of stuff wouldnt happen if it was regs to do it on properties like the Op has described. The effects are only magnified once the plug of water has fallen 5 storeys.

 

[Reg Man]

Yes have seen it in older text books etc I can understand for most installs the requirment probably isnt there but this sort of stuff wouldnt happen if it was regs to do it on properties like the Op has described. The effects are only magnified once the plug of water has fallen 5 storeys.

Absolutely agree with you. Worth while checking out Part H Building Regs.

 

[solutions]

Then again the regs are only as good as the guy that bothers to check they have been adhered too.

 

[Hen3ry]

Grateful thanks to all who have replied and much to think about. Will check the regs and see if anything is obvious. Perhaps worth getting a camera view in case a testing plug or other foreign object is restricting the air flow near the top. Otherwise, we will have to try to find an expert witness to get the building insurance involved.