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.

 

[NickH]

The poor standard of workmanship in new builds is hardly relevant to the preferred layout of a drain.
If there are existing stacks with vents, which presumably there are as this is not going to be the only bathroom, then for a ground floor WC so close to a manhole you just wouldn't have an external stack.

 

[Gilesda]

Thanks for all the replies they are much appreciated.
I'll try and load some pics later but I'm not sure they will help.
The utility and this room are an extension of the main house which is a late sixties build. The extension was built in the early eighties I believe.
It's flat roofed and very cold with little or no insulation in it. I've improved that in the utility room with a Celotex hybrid roof and Celotex on the walls and floor.
I'm doing the same in this so called bathroom and as I'm now about to batten the floor and insulate it I thought I should give a bit of thought to the plumbing.

The room has one outside wall where I was going to position the toilet. I planned to core drill through this wall and drop straight down underground. The sewer pipe runs along this wall with a manhole at each end. The front manhole has an interceptor (that occasionally blocks at its exit hole) before the sewerage goes off to a neighbour's property which has a main drain on it.

The manholes are about 700mm deep which is how far I have to dig down to connect to the pipe. I was going to cut a section of this out and put in a plastic swept Tee. The existing pipe is glazed clay which I hope will cut with a Stihl type saw. I've got an inflatable balloon type of thing to block the flow at one of the manholes while I do the cutting and connecting.
What I didn't know was having to tell the water company about this work. The house is a semi and next doors sewerage passes through my drains. There are no other houses connected to it.

I hadn't thought about the extensions foundations either. Going straight down the wall I'm likely going to hit them.
The shower outlet will be 2m from the outside wall. I was planning to raise this up on a plinth kit. I'd rather not go through the floor with any of this.

I kind of visualised it like the picture below though I don't know what an air admittance valve is or where to fit it.

"A stub stack would be typically found where an additional downstairs WC has been installed and it is often easier to bring the pipe work through the external wall then excavate the floor inside the property, it is always prudent to install some kind of access point on a stack and the one shown allows access into the drainage system and also direct access to the back of the pan should a blockage ever occur.

The image shows a sub stack that serves a toilet only, if a waste pipe from a hand basin was connected to the pipe work an air admittance valve would be required inside the property. "

 

[Rob Foster]

Thanks for all the replies they are much appreciated.
I'll try and load some pics later but I'm not sure they will help.
The utility and this room are an extension of the main house which is a late sixties build. The extension was built in the early eighties I believe.
It's flat roofed and very cold with little or no insulation in it. I've improved that in the utility room with a Celotex hybrid roof and Celotex on the walls and floor.
I'm doing the same in this so called bathroom and as I'm now about to batten the floor and insulate it I thought I should give a bit of thought to the plumbing.

The room has one outside wall where I was going to position the toilet. I planned to core drill through this wall and drop straight down underground. The sewer pipe runs along this wall with a manhole at each end. The front manhole has an interceptor (that occasionally blocks at its exit hole) before the sewerage goes off to a neighbour's property which has a main drain on it.

The manholes are about 700mm deep which is how far I have to dig down to connect to the pipe. I was going to cut a section of this out and put in a plastic swept Tee. The existing pipe is glazed clay which I hope will cut with a Stihl type saw. I've got an inflatable balloon type of thing to block the flow at one of the manholes while I do the cutting and connecting.
What I didn't know was having to tell the water company about this work. The house is a semi and next doors sewerage passes through my drains. There are no other houses connected to it.

I hadn't thought about the extensions foundations either. Going straight down the wall I'm likely going to hit them.
The shower outlet will be 2m from the outside wall. I was planning to raise this up on a plinth kit. I'd rather not go through the floor with any of this.

I kind of visualised it like the picture below though I don't know what an air admittance valve is or where to fit it.

"A stub stack would be typically found where an additional downstairs WC has been installed and it is often easier to bring the pipe work through the external wall then excavate the floor inside the property, it is always prudent to install some kind of access point on a stack and the one shown allows access into the drainage system and also direct access to the back of the pan should a blockage ever occur.

The image shows a sub stack that serves a toilet only, if a waste pipe from a hand basin was connected to the pipe work an air admittance valve would be required inside the property. "

I really would get building control involved there are a whole load of issues here
centralheatking

 

[Gilesda]

I've done 2 jobs in the past with building control involved. I had no problems but I'd rather not involve them here. I'm putting plenty of insulation in the room but the amount they ask for these days would affect ceiling heights etc. I figured it's already classed as a bathroom so I'm just improving an existing.

 

[Rob Foster]

I've done 2 jobs in the past with building control involved. I had no problems but I'd rather not involve them here. I'm putting plenty of insulation in the room but the amount they ask for these days would affect ceiling heights etc. I figured it's already classed as a bathroom so I'm just improving an existing.

Parts of this might be planning permission, or change or establishment of use, but certainly what you plan would come under building regs, which might make your property un saleabke or un insurabkle ...just friendly advice centralheatking

 

[Gilesda]

Parts of this might be planning permission, or change or establishment of use, but certainly what you plan would come under building regs, which might make your property un saleabke or un insurabkle ...just friendly advice centralheatking

That's fair enough Rob Foster, I appreciate it's friendly advice.
I'm starting to have second thoughts about doing this now. I was talking to a neighbour earlier today who has just finished building an extension on the side of his house similar to mine but bigger. He paid the water authority £800 and with building regs approval paid £2500 before he laid so much as a brick.
He's done a lot more than what I was going to do though. He removed a manhole, his front interceptor and laid a new sewerage pipe that runs under his extension. That gave him a downstairs toilet and a extension to his kitchen. Plus he got rid of his interceptor that has also like mine blocked up in the past.
Anyway I'm not sure what to do now so I'll say thanks for everybody's help

 

[Gasinspect]

Builder I work with sometimes, doesn't use the Local Authority Building control, but uses an independent Approved Inspector, much more approachable and reasonable, both in approach to issues, and cost. They tend to be very experienced and knowledgeable from what I have seen.