New toilet connection to underground.

[Gilesda]

Hi all.
I have a room off my downstairs utility room which when I bought the house was described by the estate agent as a shower room.
In reality it had a wash basin and a shower cubicle with waste through an outside wall that discharged over an outside sink. A person with disabilities lived here and I believe it had a chemical or similar toilet in there as well.
I got rid of all this and used the room as a junk store but now i want to return it to its original use. I want to install a toilet on the outside wall of the room but have a couple of issues.
Running parallel along this wall about half a metre away from the wall, obviously outside and underground, is the waste pipe for the existing house foul water. So in theory I go through the wall of the room with a 110 pipe, then down underground, cut the existing house sewerage pipe and join the new pipe to it.
Do I need some kind of soil stack on the outside of the wall?
I'll have waste from the basin and shower to contend with as well so any advice on getting the three wastes into the underground pipe would be much appreciated. Thanks.

 

[Ben-gee]

Are you planning to do this yourself?
If not just get someone round to quote.
This will need building control in any case.

 

[Gilesda]

Are you planning to do this yourself?
If not just get someone round to quote.
This will need building control in any case.

The room is already a bathroom I'm just updating it a bit. Well quite a bit really.
Yes I'm doing it myself the actual work isn't particularly difficult. What is difficult is I don't know the best way to get the three waste pipes into one 4 inch pipe to go underground. The house has an interceptor and manholes at three points where other foul and surface water is collected. Connecting to one of these would give me a much longer run of drainage than connecting into the pipe that runs just half a metre from the rooms wall.

 

[NickH]

What you will need to do, in simple terms, is dig down to the existing drain run outside, cut a section of pipe out ( it could be plastic,clay, pitch fibre or some other material), install a new plastic manhole base using connectors relevant to the existing drain material, from the new manhole run a new drain run under and through the wall and bring the new soil pipe up for the new WC.
You could run another pipe from the manhole to a new external gully for the wastes from the sink and shower.
It's all pretty straightforward, BUT like most things the devil is in the detail.
Getting the correct size and design of manhole , this will depend on the depth and how many new connections into it. Getting the right connectors for the existing pipe size and material.
Positioning the new manhole and getting the new connections in the right place.
Depending on the depth of the drain you might run into problems going through the outside wall, you might have to contend with the concrete foundations.
All very do-able though and a very common job.

 

[Ben-gee]

No need to bring soil pipe under the wall/foundations. Bring it up outside the wall and then core through the wall at the appropriate point for the wc connection as per Gilesda original post.
The manhole is the bit you were missing in OP.

Shower depends on if raised of flat to floor. Floor is better imo but will require chasing out the floor for the waste position and a channel for the waste pipe to outside, then connect to your new 4” using a short boss connector (this could be underground or overground depending on relative heights of ground/internal floor level).

If ground level is lower, then go with NickH suggestion of bringing up a gully as provides easier maintenance.

There are other things to consider, but really need to be on site to see best way to proceed.

 

[snowhead]

Is the existing underground drain shared by any adjacent properties or does it solely serve the O.P's property?

If it's shared, the Drain belongs to the local water company, you need their permission to connect to it.
The work can only be done by a contractor approved by them and there are fees involved for inspection by them.

 

[Riley]

Give us some pics

 

[Rob Foster]

do us some piccys and a diagram of existing and a diagram of planned then we can help,you effectively
Rob Foster aka centralheatking

 

[NickH]

I personally wouldn't bring a soil pipe up on the outside. It's a fairly straightforward job to go through the wall and you won't have any visible pipe work or stack outside. That's how it would be done if it was a new build or extension.
With regard to the connection into the drain, if the drain serves more than one property it is generally classed as a public sewer (rather than a drain) and you will need the permission of your sewerage provider to connect to it. Unless it's a big, deep sewer serving loads of houses you can normally do the work yourself albeit to a set standard.
You can get all the information you need from your sewerage provider and apply for permission online.

 

[Ben-gee]

Each to his own, but what they do on new builds is hardly a recommendation - especially with regards to plumbing....

An external stack is much easier to alter/maintain should needs change in the future. But I know there’s more than one way to skin a cat.