Move Soil Pipe

Ballymoney

I’m not 100% sure this is the correct forum but I have a few questions about moving/redirecting our soil pipe.

It currently runs straight down from our bathroom through a boxed in pipe in the kitchen extension. This was all done by the previous owners.

I’ve drawn a rough diagram of the rear of the house. The red is the soil pipe, blue the waste pipe, and the green is where I’d like the soil pipe to go. Also attached is a floor plan and the soil pipe is where the yellow dot is.

1. Are you allowed to redirect the soil pipe to use the same drain as the waste pipe (bath/shower/sink)? They both use the same sewage drain but just take a slightly different route to get there (I’ve run tests by flushing toilet / running shower whilst drain cover is raised).
2. The existing soil pipe runs down an internal wall and leaves the house under the kitchen floor. If we were to successfully redirect the soil pipe would it just be a case of blocking off the opening to the existing/old drain?

Not overly fussed on cost, I just want it doing because it currently sits 60cm out from the wall and will ruin my desired new kitchen layout if it can’t be moved.

Thanks

bris

Best to get a plumber in who knows the building regs in your area. When they are onsite they will give you your options.

Ballymoney

Thanks Bris. I’ll be sure to get someone in once lockdown is eased.

In the meantime it would be good to hear if anyone has undertaken the process of redirecting their soil pipe and any issues they faced.

king132

Is the waste pipe on the outside of the house a 100mm pipe? 
Waste pipes which carry bath/shower sink waste are usually only 40mm pipe.
You can attach water waste to soil pipe via boss strap or something and that is fine (40mm draining into 100mm)
You CANT have a 100mm pipe draining into a 40mm pipe. 
If the waste pipe (blue) is 100mm and the green pipe you want to put in also 100m then you can attach your toilet/ water waste to that green pipe too.
What building control might ask you to do is install an inspection chamber on the outside where the waste pipe comes down, to allow you access in case of problems.

I did something similar on my renovation where I had a en-suite put in. I had it in such a way that it backed onto the existing bathroom and the two toilets drained into the same soil pipe. The water waste connected to the soil pipe too.
Where my soil pipe connected to the outside soil pipe in (between the two floors, like yours) I attached an 110mm access branch (which gives me an additional rodding point. Above the branch a piece of pipe with an air admittance valve and then where the pipe drops I connected it to a new inspection chamber on the outside which also connected onto my downstairs WC.
I'm no plumber though. so best to check with someone.

grumbler

I don't see any problem with the suggested redirecting and blocking.

flashg67

As above, you can have a smaller waste pipe into a larger soil pipe, but not the other way round. I fitted an ensuite and all the wastes - shower and sink, go into the soil pipe inside so only one (soil) pipe shows outside.
Your intended soil pipe in green looks horizontal - it will need a vertical piece either extending above the roof line, or an external air admittance (durgo) valve fitting if you leave it shorter

Ballymoney

Really useful and reassuring replies, thank you. 

The current waste pipe setup is 2 x 40mm pipes (1 shower, 1 sink) both flowing outside into a kind of funnel which sits at the top of a vertical 70mm pipe down to the drain. 

Sounds like the best solution is to remove the 70mm pipe, replace it with a 100mm soil pipe and connect to toilet, then attach the 2 x 40mm waste pipes to it. 

Doozergirl

A photograph of the back of the house would say a lot more than your diagram and you will get a definitive answer.  😉

grumbler

It's a lean-to extension - hence the current vertical boxing in the extension and the proposed horizontal boxing instead.

Ballymoney

Soil pipe can be seen to the left of the bathroom window, coming out of the pitched kitchen roof. The 2 waste pipes (shower / sink) taps in to the gutter waste pipe seen on the right hand side, above the pitched roof. 

There are inspection chambers to the left and right of the house (the sewer pipe runs directly underneath the extension)
Hope that helps. 

grumbler

I see only the gutter downpipe on the right side. If it's the blue one that  you call  "waste pipe", then it's smaller that 110mm needed. Also, most modern houses have separate drains for waste water and rain water.