90 degree bend in foul drain

[Srp]

We’re trying to connect the sink waste from our new extension to an existing drain on our property. The original idea was to connect to the public sewer that runs along our property (which only serves next door and not us) but access and depth (2m) mean that it would cause a lot of destruction to both our and neighbour’s property (taking down a retaining wall etc) if we have to create an external backdrop.

The new idea is to run the drain around to the front of our house where the existing kitchen drain existed. This would require a 90 degree bend. I’ve spoken to building control and they seemed fine with the bend but didn’t offer a huge amount of advice.

Our builders haven’t done something like this before. Would they just need to add a rodding point, or access chamber or would a full manhole be the better option? The proposed drain would also run above an existing drain that comes from an internal stack, which building control said is fine as long as there is 100mm clearance, and wherever the downpipe from the roof goes.

Any advice?

 

[Ivor Windybottom]

You can put in an access chamber at 45 degrees, with a 45 degree single socket bend on its inlet and outlet. This splits the 90 degree bend into two, and also gives you full access for rodding and/or clearing from the chamber.

But... looking at the bigger picture, that hairpin bend within the existing chamber looks awful, and will block. It may make more sense to replace the lot with a new chamber that's between the back of the house and public sewer, so it doesn't have to go round the side then back again.

It would make sense to replace the gully too, rather than trying to connect old into new.

Connect the new chamber into the existing pipe, the blue line on your diagram. Slice it with a disc cutter then fit the right sized rubber adaptor.

Edit: Don't think you already have a chamber, were you thinking of connecting into the old gully? You definitely can't do that!

 

[Srp]

You can put in an access chamber at 45 degrees, with a 45 degree single socket bend on its inlet and outlet. This splits the 90 degree bend into two, and also gives you full access for rodding and/or clearing from the chamber.

But... looking at the bigger picture, that hairpin bend within the existing chamber looks awful, and will block. It may make more sense to replace the lot with a new chamber that's between the back of the house and public sewer, so it doesn't have to go round the side then back again.

It would make sense to replace the gully too, rather than trying to connect old into new.

Connect the new chamber into the existing pipe, the blue line on your diagram. Slice it with a disc cutter then fit the right sized rubber adaptor.

Edit: Don't think you already have a chamber, were you thinking of connecting into the old gully? You definitely can't do that!

Yeah, that is what was suggested, connecting into the old gulley. So the better idea is to go straight into the existing pipe in blue?

The complication is our water mains and another public drain running somewhere along there so access will be difficult. The manhole at the bottom of that picture takes 4 connections - 1 from the neighbours, 2 from ours, and a fourth which I have no idea where it goes (presumably from the other houses on our row). Given they’re all be 1.6-2m deep, hence why the suggestion of going in the gully.

But I’m presuming the gulley is a no go that won’t be passed by building control?

 

[Ivor Windybottom]

It's not physically possible and/or definitely wouldn't be allowed.

You need to dig down and find the pipe that's your blue line. Cut through it then connect a new chamber to it.

If your builder is suggesting somehow connecting to the gulley then find another builder.

 

[Hugh Jaleak]

I am assuming the new Gully is required for the waste pipe that can bee seen coming out at the rear of the Building in the first photo?

I fail to see why a connection cannot be made into the adjacent manhole, there looks to be ample room! Your remarks about your 'Builders' haven't done anything like this before' somewhat concerns me. Any Builder worth the title should be able to sort that out without too much difficultly, is it your 'Builder' who's telling you it cannot be done?

 

[Srp]

I am assuming the new Gully is required for the waste pipe that can bee seen coming out at the rear of the Building in the first photo?

I fail to see why a connection cannot be made into the adjacent manhole, there looks to be ample room! Your remarks about your 'Builders' haven't done anything like this before' somewhat concerns me. Any Builder worth the title should be able to sort that out without too much difficultly, is it your 'Builder' who's telling you it cannot be done?

The problem that you can’t see in the photo is that the adjacent fence is actually a retaining wall that drops down ~1m and all the current pipes and actual bench in is directly under the wall. So it’s a considerable amount of work with potential disruption to neighbours etc.

The gully that’s new is toward the back of the house in that photo, with new pipework, so yes, the original idea was to go into the existing public manhole.

But yes, your point stands. I suspect it’s time for a new builder. As they’ve not really put any effort into problem solving it which is why I’m on here!

 

[Hugh Jaleak]

You could come in from the side. Looks to be enough room to get down the side of the chamber, alternatively, a gully connection could be brought in higher up, it'll just be water going into the chamber, no solids to worry about.