Cost to divert a public sewer???

[Dougalmcdougall]

Hi,

I am looking at building an extension at the back of our house but the area where we would build has the public sewer that runs along the back of the terrace of houses. At the back of my house it’s very close to the surface and then goes down the side of our end terrace house to the road. However our ground level in the house is lower than the sewer. We step straight up from our back door 2.5ft to the garden which is above the sewer. In short, and I agree with him, the architect says the only option (other than having a public sewer pipe running through our extension at knee height) is to enquire to Thames Water to get them to move it round the extension. Extension being roughly 3m x 7m so that is the very approximate diversion length.

Does anyone have any idea of the cost of diverting a public sewer? Are we talking £5k or £30k? £5k would be a big pain but managable but £30k not...

 

[Ian H]

Does it drop deeper down the side to allow your drains to run into it?

 

[Dougalmcdougall]

Yes it turns through a right angle at the corner of the house and then slopes down along the drive at the side to the road. The man hole at the front of the house is pretty deep but the one at the back is near the surface. At the back of the house the sewer runs parallel to the houses about 4ft from the back wall. There are three houses that feed into it. Mine being one on the end.

I’ve no idea how much it could cost and neither did the architect - he said it could be a few thousand but could equally be 10s of thousands if Thames Water do it all rather than let us do it under their supervision. Hence wondering if anyone has done this before and what it cost them?

 

[Ian H]

If it were me I'd be thinking to relay it up from the manhole at the front with a steady fall, manhole at the change of direction then renew it lower under the extension.

There will probably be a dropshaft just behind the manhole at the front to get it to the lower level.

It's very difficult to guess a price but unless there is something difficult in the way I'd be thinking 5k would be plenty.

 

[Notch7]

I did a job in Leatherhead area, had to divert sewer. Thames water.

It cost about £3k, but it was minor and done under a form of build over agreement.

You will need clay pipework and brick manholes if thats what there is now.

CCTV inspection before and after.

You can use your contractor.

Go to thames water site, you can download forms, see developer services.

Your best bet is to do a drawing showing existing and proposed, send to the developer services and somebody from technical will get in touch, to tell whats possible.

 

[noseall]

You will need clay pipework and brick manholes if thats what there is now

Not necessarily.