Moving a lateral drain - feasible?

[elliott75]

See images for some clarity.

We have a lateral drain which runs horizontally across the back of our property, about a metre from the kitchen wall. The blue annotations shows the drain cover. This doesn't appear on Thames Water's maps though. It appears to run under our 80s flat roof extension and we are in the middle of the lateral drain which certainly goes to both direct neighbours if not further.

We are hoping to do a downstairs renovation, and my other half is very very keen on "squaring off" and taking back that corner, which would be really useful to a new open plan kitchen. That 4x3 square, bottom left of the floor plan, between the kitchen and the extension, which contains the drain cover.

I've learnt a lot about lateral drains and build over rules, and I believe we'd need to move the lateral drain basically. And I cannot comprehend how we'd even manage to do that practically, to be able to then lay foundations on that square and extend.

The inspection cover is right up against the boundary, and I'd imagine it needs some sort of sharpish left turn into our garden, before then doing a sharpish right turn, under our flat roof property to join up again with the neighbour on the other side. That's before even thinking about how to get access to the drain under the flat roof.

Or, could we build over it and have an inspection cover in our kitchen, tastefully hidden? We already have one for our private drain which runs into the lateral drain. I can't imagine TW would be okay with that?

Before getting CCTV survey, I wanted to ask for advice to see whether I'm probably right and its a nonstarter, or I'm just being unimaginative and its worth pursuing.

Also, if this doesn't appear on the TW asset location map, can I get them to survey it, so they can add it???


Thanks in advance.

 

[freddiemercurystwin]

They won't survey it so forget that, if you look on the TW website you will find all of the homeowner build near/over criteria, they won't allow a shared manhole within your extension so it's likely your only option is to shift the sewer outwards into your rear garden which will likely involve your neighbours input/permissions etc!

 

[noseall]

I cannot comprehend how we'd even manage to do that practically, to be able to then lay foundations on that square and extend.

We've done stuff like that. Difficult but not impossible.

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• noseall
• 19 Aug 2022

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• noseall
• 19 Aug 2022

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• noseall
• 19 Aug 2022

A lot depends how deep the existing drains are...?

 

[Ivor Windybottom]

Even if not impossible, it sounds like a heck of a lot of work for perhaps 3sqm of space!

If you really are short of space then extend the kitchen into the lounge internally then extend the lounge out further into the garden. It's already past the pipe and flat-roofed anyway so there's nothing stopping you.

Or sell it and buy a bigger house?!

 

[elliott75]

Dear Mr Bottom,

Would that be allowed? The flat roof part is already an extension out. I didn't think you could extend where there is already an extension? Or is that an oversimplification. Something I hadn't considered, either way, and likely worth considering.

I reckon the extra space gained would likely be 3x4m ish. At least 10m2.

 

[Ivor Windybottom]

You may or may not need planning permission. You'd need to check the permitted development guidelines if you're planning to build without permission. Honestly I don't know what is and isn't allowed.

Looking at your photo, the owner of the green house next door must already have a fairly dark back window so you may struggle to get permission to extend further, to avoid making them any sadder.