Multiple bathroom waste connections into stack

[JonHeath]

Hi all,

I'm looking for a bit of advice on designing multiple new waste connections into an internal soil pipe.

I'll have 3 wastes (sink, shower, bath) that I want to join into a single 50mm pipe (running at a slight downward angle on a horizontal. The 50mm pipe then connects into the internal vertical stack.

Is this the right way to do it? Can I have that many connections into the 50mm pipe. I assume that 50mm pipe is the right choice for that run? Do I need a particular type of trap on the sink, shower, bath if I do this?

Finally I'll also have a 110mm connection into the stack for the toilet also. The 50mm pipe described above will connect around 200mm lower into the stack than the 110mm connection for the toilet. Presumably that is OK?

Many thanks.
Jon

 

[Newboy]

It's not a good idea to have combined wastes - one blockage and you have a bath or shower tray full of gunk. What the distance to the stack from each appliance?

 

[JonHeath]

It's not a good idea to have combined wastes - one blockage and you have a bath or shower tray full of gunk. What the distance to the stack from each appliance?

The stack is the other side of the wall in the next room. It will be around 1 metre from the shower, 3 metres from the bath and 4 metres from the sink. Doing an individual run for all of them is very difficult with the access available.

Is what I'm proposing compliant to regulations?

 

[Newboy]

The attached maybe of some use http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADH_2002.pdf pages 7,8 & 9.

Personally i'd avoid joining all three appliances to the same waste run. If you do go down this route then I'd either fit anti-vac or waterless traps and ensure that you have good access to clear any potential blockages. ensure that you get the falls right on the pipework & clip the pipe to avoid any dips. In some cases it would help to fit an aav at the head of the run.

 

[JonHeath]

Thanks for the info, I'll have a read through that.

Just to be clear my plan was to drop all 3 runs into the 50mm pipe individually. They'll be dropping into the top of it. I could potentially swap the 50mm pipe for a 110mm pipe that connects to the stack instead. Presumably that would be better?

 

[JonHeath]

Thoughts on the horizontal 110mm plan connecting into the stack?

Thanks
Jon

 

[Hugh Jaleak]

If you've room for a 110mm pipe it does beg the question why you cant do individual runs, but if 110mm will fit its far superior to using 50mm in this case. Problem often arises with combined wastes after a period of use, when they start to clog up with soap, hair etc, then the contents of one appliance, when discharged, reappear in another.

I went to a property recently where a pretty full bath had been let go, the waste was partially blocked (and also had a number of 90deg bends in the run which didn't help...), and the water came back up through the shower waste. By the time the occupant had realised what was happening, (she'd gone into the bedroom), the shower tray had overflowed and water was dripping through the ceiling into the room below. Extreme case maybe, but it can happen and shows the perils of appliances on combined wastes.....

 

[JonHeath]

Thanks for the reply. Yeah I definitely don't want that

I've tried not to bore you all with too much detail, but I'm doing an extension at the moment. That gives me good access to below the bathroom as the ceiling is down and to the stack. The situation I described initially is my end state when I get to the bathroom. At the moment I've just got the existing 2 waste pipes to deal with. I'm trying to set it up so that it's future proof as when I change the bathroom (probably next year) I won't know until then exactly where the pipes will run. I'm able to put this 110mm pipe in horizontally next to some other boxing where I've got a new steel. This will all get boxed in soon, but will be accessible by lifting the floor above. So I do have the room to do individual runs but I'm not ready to do them and this opportunity of access will disappear. In the future I'd lift the floor and be able to see the 110mm pipe below the joists and drop pipes into it.

I actually think this 110mm solution could be better anyway as the individual wastes will drop into the top of the pipe, so discharge back up would be near on impossible. Whereas individual pipes would need to sweep to the stack and be more liable to blockage.

 

[Hugh Jaleak]

Detail is good, as it allows us to see the bigger picture and advise accordingly.

Superb. Yes, run in 110mm, with an access cap on the top end. Drop your wastes into that, and I'd fit an anti vac trap on the furthest appliance though just for good measure.