sewer pipes and build over agreements

[TryC]

Hey All,

 

Just looking for a bit of guidance, please.

 

If your build is near a main sewer pipe, do you need a build over agreement? e.g., extension is within 3 metres of the pipe?

 

Do builders usually have an idea of where pipes might be before digging or would they assist you find out where they are by doing a test dig or perhaps, do they advise clients that there are actually services that you can engage that tell you were they are? 

[nod]

It sends what you mean by sewer pipes 4-6 inch pipes are easy to divert or build over Larger main sewage runs arnt But are mapped out and easy to identify (manhole covers)

[TryC]

31 minutes ago, nod said:

It sends what you mean by sewer pipes 4-6 inch pipes are easy to divert or build over Larger main sewage runs arnt But are mapped out and easy to identify (manhole covers)

sorry, maybe it's early but reading your response a couple of times, I'm still not sure what you mean?

[nod]

28 minutes ago, TryC said:

sorry, maybe it's early but reading your response a couple of times, I'm still not sure what you mean?

Your probably better putting up a drawing with your question 

[johnhenstock83]

so, let's clarify a few things, it's a language issue:

 

a sewer is a "larger" underground construction to help facilitate the drainage of waste (and rain) water to a processing facility. sewers are owned and maintained by the water authority, they're usually deep, collect drainage from multiple properties/estates etc. it is very unlikely that a sewer main runs under your home or through your back garden, but not impossible. you can't build over them and they can't really be moved, it's extremely expensive and disruptive.

 

a drain is a "smaller" underground pipe that takes household waste (and sometimes rainwater) to a nearest sewer. in doing so, it might travel through people's gardens and will probably have several inspection chambers along the way. the rule of thumb is that if it serves more than one property, it is a public drain (or a lateral one), but building over (or even re-routing) is possible with the right paperwork in place.

 

then there are private drains, which only serve your property. up to the first inspection chamber ("manhole"), you can do pretty much what you want without asking for permission: build over, re-route etc.

 

in your case, you will need to find out where your private and/or public drains are located, the main sewer is of less importance, unless the manhole is located in your backgarden. look for any inspection chamber/manhole covers at the back of the house, in the back garden, front garden or any side alleyways. if you make a drawing showing your property in relation to these (and the pipes leaving your house), we will be able to tell you what you're dealing with, but the only way to know exactly what's under the ground is to get a drain survey (CCTV), costs around £300.

Edited September 30, 2023 by johnhenstock83

[George]

I've always understood a drain to be a pipe serving an individual household and a sewer is a pipe serving more than one household.

[Gus Potter]

On 29/09/2023 at 22:26, TryC said:

Just looking for a bit of guidance, please.

Hiya.

 

Here is the link to a post I made a while ago about how I go about getting build over permissions and the different types of sewer.. I have tried to paste the link but if you click on the pic below it takes you to the thread where I posted info. Scroll down a bit and you'll get to my post.

 

Big thing here is you need to know what the different types of sewers are.

 

A private sewer is a drain that only serves your house.. you tend to own that. A public sewer is one that serves more than one house. You often see them up the back of a row of terraced houses. Often at the end of the terrace they turn towards the street and run into a main sewer.. which is a big (don't want to be rude) often deep large diameter pipe with potential very costly problems attached. Your 3.0 m rules are often out the window when you encounter a main sewer.

 

To get best advice you need to give more info with a drawing and tell us what kind of drain it is. If you read my old post this should help you navigate this minefield.

 

Have a read at that and then we can maybe help you a bit more?

 

 

[TryC]

please excuse the crappy drawing skills (or lack of).

 

there is a manhole located in the garden but the architect and builders just assumed the pipes would run in line across the garden, but it unfortunately doesn't not and slopes up towards the neighbours garden, and I think they may have built over theirs themselves. 

 

 

 

[Mr Punter]

You need to determine the depth and route of the sewer and the extent and depth of your proposed extension foundations.  Show this on a properly scaled drawing.  If there is a clash, you may be able to deepen your foundations locally or bridge over the sewer.  Diverting the sewer would be a last resort.

[kandgmitchell]

Go on the website of your local sewerage provider - Thames Water, Anglian Water etc and head to the developer pages. There you will find information about building over or near sewers. "Build over" is a bit confusing as it's not just the pipe itself but the 3m zone either side. Most providers now do a "self certification" approach where as long as you meet all the criteria set out then you can proceed (subject to normal building control requirements for drainage) without a formal build over agreement. If your proposal doesn't qualify for self-certification then they'll expect to see plans of how the pipe relates to the proposal, depth of the pipe, foundation arrangements, etc etc. There's a fee involved and you'll have to wait for their approval.

[Chathura]

On 29/09/2023 at 22:26, TryC said:

Hey All,

 

Just looking for a bit of guidance, please.

 

If your build is near a main sewer pipe, do you need a build over agreement? e.g., extension is within 3 metres of the pipe?

 

Do builders usually have an idea of where pipes might be before digging or would they assist you find out where they are by doing a test dig or perhaps, do they advise clients that there are actually services that you can engage that tell you were they are? 

 

1. First contact your water & sewerage company and try to obtain maps of the public sewers in the area of your property.
2. If they have it, then you can simply provide that to your builder.
3. If the water company doesn't have maps or up-to-date records with them about public sewers in your area, you can open the inspection tank (manhole) in your property and see which side is upstream (direction from where water/soil flows into the manhole). 
4. Then talk to your neighbour on the upstream side, and pour a bucket of water in their inspection chamber (manhole) and see if that water flows through the manhole of your property.
5. If the water you poured flows to the manhole of your property, then it is a public sewer. This means you need the approval of the water & sewerage company to make any diversions.

Example:

 

1. You will have to lodge an application for the approval process and make initial payments.
2. As far as I know, since 2020, the water companies must comply with Design and Construction Guidance for foul and surface water sewers  https://www.water.org.uk/wp-content/uploads/2021/07/SSG-App-C-Des-Con-Guide.pdf
3. Therefore, they will just offload the entire pain of checking these standards, preparing all the technical documentation and buying the "Adoptable" products that comply with BS/Kitemark specifications while they also charge you for just issuing the approval.
4. In our case, neither our architect/engineer nor the builder was very familiar with these (the only thing that the builder could do was curse the water company people saying that they were only interested in the money). Therefore, I did all these technical documents myself.

The water company however will send you a list of these documents:

• Longitudinal sections
• Manhole schedule
• Site layout
• Manhole construction details
• Pipe bedding details
• Lintel details
• Your land title etc
• CCTV survey of the drains 

Once they are satisfied with this, they will give the green light to start work. Then you have to pay another amount for on-site inspection. Then your builder can work with the on-site inspector of the water company and finish the work. 

 

Please try to prepare these in advance if possible. Otherwise, it will cost you a lot of time depending on the water company in your area.

 

In our case, they asked us to put Clay pipes for the new sewer line also as there had been cases where plastic pipes had blown when the pressure washer was used by them (we used Hepworth super sleeve). Also, when buying Plastic inspection chamber products, they will ask you to buy the products marked as "Adoptable".