Waste pipe into ground floor bathroom

[zzzkr]

Hey everyone,

Hoping someone can help me out with this! We’re planning to add a second toilet downstairs, and the only spot that works is in the garage. It'll eventually have a toilet, sink, and a small shower.

I've already dug up a bit around where the waste pipe comes out of the house, but here’s the issue: there’s a rainwater pipe running right underneath the waste pipe. A bit further along, the waste pipe shifts slightly to the right and also goes a bit lower, but it’s still about 6 cm higher than the rainwater pipe at that point.

Any ideas on how I can make the connection work with the rainwater pipe in the way? I’m new to this and I would really appreciate any hints or tips to pull this off.

I’m not tackling the full bathroom just yet—just trying to sort out the waste pipe so I can pave the path for now. Also, I’ve hit a dead end with building regs because the company that was doing the inspections has gone bust, so I’m a bit stuck there.

Can I use a boss fitting like that, horizontally? Or is there an alternative to pull that off? So I can connect the shower, sink from the top and the toilet to continue through it to the outside?

Do I need to vent this?

Would really appreciate any advice! Cheers!

 

[blup]

If the surface water pipe interferes with making the sewer connection, break into the pipe as well or even move it, just maintain the fall for both.

 

[thomp1983]

As I've marked above, if the orange line is the rainwater and the purple the drain can you not dig out and remove the access point, replace with a suitable fitting and add a new access to the right through the wall?

 

[Hugh Jaleak]

I very much doubt you'll be allowed, (and I wouldn't want to put in), a blind connection for a WC. I would expect you'll need a small inspection chamber at the point where you break into the existing sewer, if you can find one with the lateral inlet at the same invert (level) as the through channel this will probably help.

I'd keep the pipework going into the house as low as possible to give yourself some leeway with the shower waste, especially if you want the Tray as close to the floor as you can.

 

[zzzkr]

If the surface water pipe interferes with making the sewer connection, break into the pipe as well or even move it, just maintain the fall for both.

Thanks! I think this is actually a great idea. I’ll just move the surface water pipe a bit to the left to make space for the waste pipe to go over it, and then connect everything with a Y-branch using a slightly angled bend fitting. Does that sound right?

 

[zzzkr]

As I've marked above, if the orange line is the rainwater and the purple the drain can you not dig out and remove the access point, replace with a suitable fitting and add a new access to the right through the wall?

That photo was more of a reference for where the pipes start and how they run on top of each other. I will be connecting into the waste pipe a few meters down where the garage is and where the waste pipe shifts to the right a bit to make space for the rest of the gutters to connect to the surface water pipe.

 

[zzzkr]

I would expect you'll need a small inspection chamber at the point where you break into the existing sewer, if you can find one with the lateral inlet at the same invert (level) as the through channel this will probably help.

Something like this you mean?

I'd keep the pipework going into the house as low as possible to give yourself some leeway with the shower waste, especially if you want the Tray as close to the floor as you can.

It’s 44.5 cm from the top of the waste pipe to DPC level. I’ll make the fall from the connection point into the house, and since it's only 82 cm from the waste pipe to the wall, I’m hoping the waste pipe will be deep enough to avoid the main water pipe that runs through the garage floor.

 

[Hugh Jaleak]

Something like this you mean?
View attachment 357379

Yes. Otherwise you run the risk, should the WC block, you'll struggle to unblock it, and you really don't want to be trying to do that from inside the property....

I would look at bringing the soil pipe up in a corner, then connecting everything in on the vertical section.

 

[zzzkr]

The waste pipe (the one on top) is too close to the neighbor's garage.

I'm not sure what to do in this situation.

Can I move the surface water pipe to the left, similar to the waste pipe, and then bring it back to the center? And can I move the current waste bend about 1 metre down the line to align the mini chamber with the hole in the wall?

Something like this?

 

[Hugh Jaleak]

Easiest way around that. Graft a 90 junction into the Foul run opposite where you want to come out the house with the new connection, go straight over to your house, and fit a Mini Chamber on the straight run.

 

[zzzkr]

Good call. Can I do y junction instead of 90? The only issue is the waste pipe is almost same level with rain pipe. I could do y branch and connect the mini chamber with an adjustable bend into y branch onto the main waste pipe

 

[zzzkr]

This is what I managed to do today. Will this be okay? I still need to core drill the hole through the foundation.

 

[Hugh Jaleak]

Looks good to me. I'd bed the chamber on some semi dry concrete, and leave around a minimum 10mm gap between the pipes where they cross, to allow for any slight movement. Allow expansion room for pipe through foundation as well, and ensure no weight is bearing on the pipework.

 

[zzzkr]

Thank you so much, good sir. You have no idea how much your advice has helped.

 

[zzzkr]

Any suggestion on what will be the best way to seal the gap left around the soil pipe through foundation. Something that would keep it in place and prevent water or moisture going in. Thanks