Would you buy a house built over public sewer?

[mumtobe245]

We are in the process of buying a house. Main appeal of the house to us is the location (short commute and school run) and that it’s at a price point which allows us to do a large kitchen diner extension at the back (where currently there is a lean-to)

The searches have come back and suggested the said rear extension (which is the current lean-to) will need to be built over a public sewer line (see map attached, house marked in red line). This is giving us second thoughts on the property.

I am concerned about the cost and efforts involved in building an extension over a sewer line (there is no a build-over agreement at the moment). Also, wondering if there will be any risk with houses being built over a sewer line (e.g. smell?)

What would you do in our situation? Would you proceed or pull out?

What is a "sewer line" - a pipe carrying sewage? It wouldn't necessarily bother me if no existing issues. Can you speak to neighbours, check with council whether any reported issues, etc?

It wouldn't put me off. Fairly easy to get a build over agreement from the water company and then the builders will just need to ensure they follow the requirements set out by them.

We had an extension close to the sewer, the only restriction was that our foundations had to be lower than the sewer was. Builders also had to bridge over the soil pipe from our house out to the sewer, no issues.

yes see if there are reported issues- but I would have thought that was relatively common. Sewer pipes etc. We have ours going diagonally through our garden and the house was built 1879 so presumably the pipes date from Victorian times like most of our sewers in England anyway.

This is very common as people extend into their gardens. You will need a build over consent from the sewerage authority for the area (ours was Thames Water, cost about £250 or so at the time). A good builder or architect will be able to advise. You might want to get a drainage survey done as well as whatever other survey you are getting to tell you if the sewer is in good condition, eg whether there are any broken pipes which would need fixing first (which the sewerage company should do for a public sewer).

This would not put me off at all.

We had a problem with an extension at a previous house where the sewer from three other houses ran under all our garden into the main sewer in the road. Our plans would have meant that the extension would have gone over the manhole in our patio cover which accessed the sewer so Severn Trent Water refused to give permission - not that I wanted a manhole cover in my kitchen! We had to amend our plans from a full width extension to a smaller one about 2 metres shorter to leave access to the sewer outside.

It’s a good job we did as a year or so later we had issues with a blockage causing sewage to flow into our garden after a neighbour put disposable nappies down the toilet!

I work in drainage!

You need to be very clear on who is responsible for inspection, maintenance, repairs and replacement of the sewer; for clearing blockages and damage cause upstream by blockages and damage in the pipe. Don't assume that this is not householder responsibility

How deep is it?
Is it deep enough to take the load of an extension ?
Why is there a no build clause now?

Does it carry clean or waste water?

("Sewer" is used for pipes carrying both)

.

very common scenario, most likely your builder will create a manhole outside the house to route through sewerage your property to public sewer, so public sewer will be covered by your flooring - this is just an example, your architech may have better plans - but nothing to worry, no smell etc. Our current house is similar to 12 which is start of sewer and we have built a large extension.

image attached

Thanks for explaining. Can I please make sure I understand correctly - Does this mean we will need to have the sewage pipe (foul water) moved to be outside the extension, and build a manhole to access the new pipe?

Thanks for sharing. This is very helpful.
Can I ask if you did consider moving the sewage pipe to be outside the extension, instead of keeping it in the original location and shorten the extension to allow access from outside?

We did donkeys years ago - solution was to have manhole under the dishwasher, so if there ever was a problem (there wasn’t) we could have just pulled out the dw to access manhole.

We have a similar situation. Provided there is no damage to the sewer pipes, the main issue, as I understand it, is that you mustn't build over any access manhole to the sewer.

if you intend to do so, then a new access point must be dug and they don't come cheap!

It wouldn't put me off buying the house in your case.

@SarfLondonLad thanks for this. The property currently doesn’t have any access manhole to the sewer, so does that mean we might not need to create one if we build an extension?

@at84 Thanks for explaining. Can I please make sure I understand correctly - Does this mean we will need to have the sewage pipe (foul water) moved to be outside the extension, and build a manhole to access the new pipe?

You can not change original sewage pipe, but your house drainage will connect to it like I showed you in the picture. for example, from your bathroom drainage will connect to manhole outside your extension and from that manhole, another pipe connecting back to main sewage pipe. As mentioned, this is one of the solutions, other solution would be to connect direclly to main sewage pipe from inside the house itself but then you may have to keep a manhole somewhere inside the property.

No, at the time that was not considered by the builder or by us! In some ways I preferred our final design, being a little narrower it was cheaper so we were able to afford to add an all weather verandah ( with lighting and heaters) off the lounge. This became my favourite space to enjoy a drink after work!