New Drainage

[Tom_Thumb]

Hi all,

I’m currently looking to have some new drainage installed (see green lines on image below) which to my limited knowledge, will involve excavating beneath the patio, excavating beneath the toilet floor to expose existing pipe work, core drilling through the walls and running new pipe to branch onto existing pipe.

Main questions, is this feasible, is it a huge job, and what trades would be required ideally?

Note : It is a combined drainage system so no issues mixing surface water with foul, as far as I’m aware?

Many thanks in advance.

Tom

 

[noseall]

Hi all,

I’m currently looking to have some new drainage installed (see green lines on image below) which to my limited knowledge, will involve excavating beneath the patio, excavating beneath the toilet floor to expose existing pipe work, core drilling through the walls and running new pipe to branch onto existing pipe.

Main questions, is this feasible, is it a huge job, and what trades would be required ideally?

Note : It is a combined drainage system so no issues mixing surface water with foul, as far as I’m aware?

Many thanks in advance.

Tom

View attachment 390560

Always f£asable.

The first thing a builder would look at is the depth of the drains. Punching through walls is not an issue. If the drain depth means punching through the foundation concrete, that's a different matter.

We'd probably take the proposed toilet line beyond the loo and out to the rear wall and fit a small stack there with a RW gully to the side to collect the rainwater drop.

 

[Tom_Thumb]

Thanks @noseall.

Haha f£asible is right!

Just so I’m clear, everything other than the green lines is existing, rather than proposed. Not sure if that changes things?

I see what you’re saying about a small stack, however my hope was that this could all be concealed beneath ground level, maybe with some sort of service hatch in the patio to give some access…

I know it’s probably quite hard to say without seeing it in person, but at least your comment has given me the confidence that it can be done on£ way or anoth£r

 

[Ivor Windybottom]

You'll need a number of inspection chambers and/or rodding points to make that crazy route.

What are you actually trying to achieve? I'm guessing you're aiming to add rainwater to the sewer.

If the best solution really is to go under the floor then I'd suggest that removing and refitting (or replacing) the toilet is probably more sensible and cheaper if that toilet is the sole reason you've decided to create the crazy looper in your design.

You'll need a trapped gulley. It's not acceptable to couple the sewer directly to the downpipe, downpipes aren't airtight at their joints and have an open top, so you'll have a permanent stink all around it if you do that, as it will naturally become a sewer vent pipe.

Start by explaining the aim, rather than jumping straight into your design for doing it. There are probably better ways, once your intention is understood.

 

[Ivor Windybottom]

I'd go straight through the wall to the left of the new gully, immediately followed by a 45 degree bend to the right then join into the pipe somewhere under where your feet go when sitting on the loo. But feasability depends of the exact layout, which the diagram given doesn't provide. Perhaps buy a 45 corner to put on the floor next to the loo to get an idea of how sensible or otherwise.

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This is designed to block foul air and is roddable after pulling out the centre section. So no further access points needed.

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I don't know whether you'd need to insert a lintel into the wall above the pipe.

 

[Ivor Windybottom]

Total cost is £57.84, just to wind up the resident tradies!

 

[Tom_Thumb]

Thanks for your input @Ivor Windybottom

My diagram was more to get a grasp of if the concept was feasible, rather than the exact layout, but you make a fair point, I should have explained my intention first.

Basically, I am hoping to route the outside RWP through the existing wall below ground level, and couple up with the existing main drain at some point.

The RWP location can quite easily be moved by re-configuring some guttering, and could be located more or less where my green line actually crosses the existing wall, which might simplify things a bit…

I am hoping to do all of this, whilst containing the upheaval to just the patio, the bathroom floor and likely the utility floor.

This is an issue created by an extension the previous owner had done, where there was basically no drainage installed for the RWP, other than a pipe that goes about 1m underground then stops ‍ So I am looking at the best way of having it put right.

Hope that makes some sort of sense!

Michael

 

[Ivor Windybottom]

The RWP location can quite easily be moved by re-configuring some guttering, and could be located more or less where my green line actually crosses the existing wall, which might simplify things a bit…

That would be a very good plan.

Don't let the existence of the toilet constrain you, it would probably need to come out to do this anyway.

The feasibility very much depends on the pipe depth. Your floor should be higher than the ground outside, and any gully needs the pipe to be a minimum depth below the ground. Even if you can access that chamber, it only tells you the depth at that point, the toilet end will have to be a bit higher but may be much higher.

You might need to remove the toilet and have a look or feel down the pipe before planning further...

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Repeating myself here, but it's important... Don't couple the downpipe directly to the sewer!

 

[noseall]

Thanks @noseall.

Haha f£asible is right!

Just so I’m clear, everything other than the green lines is existing, rather than proposed. Not sure if that changes things?

I see what you’re saying about a small stack, however my hope was that this could all be concealed beneath ground level, maybe with some sort of service hatch in the patio to give some access…

I know it’s probably quite hard to say without seeing it in person, but at least your comment has given me the confidence that it can be done on£ way or anoth£r

You could have a stub stack internally and boss the rest of the bathroom into it?

 

[Tom_Thumb]

Thanks @Ivor Windybottom , I’ll keep those green gauntlets in mind!

Have you got any images that would show a stub stack configuration in more detail @noseall ?

How would the external RWP route into this system?

Thanks

 

[Ivor Windybottom]

A stack is as the name suggests a vertical tower of pipe and connectors.

90 degree rest bend at the bottom...

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Toilet and gully connect into 90 degree tees facing whatever direction they come from...

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There are restrictions on the proximity and angle of toilet to other inlets, e.g. to stop jobbies from the bog firing out of the building into the gully outside. It's all in the building regs, a free download from gov...

Drainage and waste disposal: Approved Document H

Building regulation in England for foul water drainage and disposal.

www.gov.uk

These limits may or may not mean this is possible, depending on the depth.

The top either continues up and out of the roof as a vent (usually boxed in) or terminates inside the bathroom with an air admittance valve, in your case tucked away behind the bog under the tank.

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All utterly dependent upon there being enough vertical drop under the floor to accommodate all this. The toilet inlet can be just above floor level though, then a 90 degree adaptor takes it sideways (with a slope) from the back of the toilet into the side of the stack...

https://www.screwfix.com/p/mcalpine-macfit-rigid-90-angled-wc-long-pan-connector-white-305mm/95284

All amateur knowledge, without warranty! I'm sure someone will be delighted to correct me if I've said anything in contravention of human rights or something.

 

[Ivor Windybottom]

Like this...

Your outdoor gully would tee into the same vertical pipe stack below the floor, then the 90 rest bend, into the existing pipe.

But check the building regs. No jobbies firing outside allowed. The loo may need to be below the rainwater, in which case you need enough depth to do it.

 

[noseall]

Thanks @Ivor Windybottom , I’ll keep those green gauntlets in mind!

Have you got any images that would show a stub stack configuration in more detail @noseall ?

How would the external RWP route into this system?

Thanks

Tha stub stack could be integrated into some smartly designed WC with concealed cistern etc.
The drain would still need to pass through the wall to pick up the rainwater.