Can I add a new bathroom a distance away from SVP?

[SomethingSomething]

Hello all,

We purchased the property a year ago and we're now finding that we'd really like an additional bathroom downstairs in what was originally planned as a utility room by the previous owners. The extension is split with a concrete block wall in the middle between the utility and dining room extension roughly 3mx5m and was built in approximately 1970 with planning approval granted.

Looking for your advice please as we are new to the process of bathroom plumbing from scratch. There appears to be some level of drainage already set as the utility room has a sink and washing machine draining on either side of the wall (original house and the extension utilty side where we now have the washer and dryer located.

We spoke to B&Q, who advised us that the toilet can't simply connect to the drain outside the window (see picture of inspection chamber). They advised that we would need to dig up the utility room concrete ground signficantly (to ensure there's a proper angle in the pipework) and connect the toilet to the existing SVP via underground pipes which is at the other end of the utility room from where we would like the toilet to be placed, making this a difficult and expensive job. They say we would need to have a vent as directly discharging to sewage without vent can cause backflow.

I hope this makes sense, please see attached pictures including floor plan which I'm hoping should explain this more clearly.

Please can we ask for your advice on the best way to connect the toilet to sewerage and any other considerations for plumbing we'd need to make?
Any input on estimated price for works and/or anything regarding building works etc would be very helpful thank you. We're also not sure on how deep the stud wall will be and hopefully won't take up too much space as bathroom is already looking very small.

P.S. The wall is knocked out as the pipe was previously enclosed in the wall and was leaking (Asbestos) SVP replaced with new PVC pipe. Apologies for the mess.

 

[Hugh Jaleak]

I am pretty sure B&Q Staff will not have a clue what they're talking about a lot of the time.

First thing is the drainage. The Manhole you have pictured, when you flush the upstairs WC, does the discharge appear in that chamber?

 

[SomethingSomething]

Thanks for your prompt message!

No unfortunately the manhole seems to be for the downstairs sink and washing draininge. We have the black svp connected to the upsrairs toilet directly.

Thank you

 

[Hugh Jaleak]

No unfortunately the manhole seems to be for the downstairs sink and washing draininge.

Need to establish if that Manhole is taking Foul (sewage) or Rainwater. If the Sink and Washing Machine are going into it then it should be Foul but I'd want to be 100% certain before committing to connecting into it.

Lift the Manhole cover, and get someone else to flush the upstairs WC, can you hear any discharge downstream of the chamber?

 

[SomethingSomething]

Thank you for you reply and apologies for the delay in responding back. I was very mistaken. Having lifted the manhole cover all toilet waste goes to that sewage line under the manhole cover! I hope this is good news B&Q told us that we'd need another vent pipe at the location of the toilet if we were to direct sewage over there.

 

[Mottie]

In our old house, we had something similar to your inspection chamber. We were the end house in the street and the drain flowed backwards, under our extension bathroom which was a proper bodge job and probably not built to regs - I think it was even single skinned! It was there when we bought the Victorian terrace. When we changed the WC, we had to fit a different setup to original. My Brother in law who was a builder did it for us. He broke through the chamber wall and added the soil pipe so that everything just plopped into the trough and ran back in the opposite direction to the way your one flows as per the picture. If it worked for us, I’m sure yours would work in a similar fashion especially as you can direct your pipe in the direction of flow.

 

[denso13]

They say we would need to have a vent as directly discharging to sewage without vent can cause backflow.

It depends on the distance the new WC will be from the vent. Should also have LABC involvement, Building Control will have a view on it as well.

 

[Hugh Jaleak]

If new WC is to go the other side of the wall from the chamber, then a suitable connection into the chamber will suffice. Needs to be done to allow smooth flow of discharge through the chamber to prevent solids building up on the benching, but provided the distance from the invert of the drain to the crown of the WC trap is less than 1.3m it shouldn't be an issue.

Existing drain remains vented at highest point, so I don't see Building Control having any issues.