Public sewer

jimmysaver

Hello,
I'm in the process of purchasing a property and the drainage search has shown that there is a public sewer running through the garden of the property. Have attached the picture from the search here. 

As you can see, it looks like this runs under where the property has been extended and also slightly across where we would likely extend the property (into the side return). 

Not sure if this is something to be concerned about and whether it would impact our ability to extend the property in the future?

Any advice welcome!

vacheron

You would just need a build over agreement from your local water supplier. The previous owner should have obtained one when they built over it the first time. we had to arrange one when we identified that an access chamber we were planning to build over was actually a public sewer during our extension build.

Do you have any documentation from the first build to see if this is included? If not, the water company can tell you if this exists. 

Grumpy_chap

Looking at the plan, the scale is such that the existing extension is probably short of the existing sewer so it is possible that no previous build over agreement was required.

The OP will require a build over agreement for their new extension.

Section62

Grumpy_chap said:

Looking at the plan, the scale is such that the existing extension is probably short of the existing sewer so it is possible that no previous build over agreement was required.

The OP will require a build over agreement for their new extension.

The requirement is for within 3m of a public sewer, so if the plan is accurate an agreement would have been required unless at the time the extension was built the pipe was not a public sewer.

jimmysaver said:

Not sure if this is something to be concerned about and whether it would impact our ability to extend the property in the future?

Have you made enquiries with the planners whether you'd need planning consent (I think quite likely) and if you do, whether they would be likely to approve an application?  Do you know how much of the existing building is extension?

Grumpy_chap

Section62 said:

Grumpy_chap said:

Looking at the plan, the scale is such that the existing extension is probably short of the existing sewer so it is possible that no previous build over agreement was required.

The OP will require a build over agreement for their new extension.

The requirement is for within 3m of a public sewer, so if the plan is accurate an agreement would have been required unless at the time the extension was built the pipe was not a public sewer.

Yes, I know.
And, given the scale of the plan, the extension is quite possibly 3 m away from the sewer as marked so still sufficiently short of the sewer that a build over agreement was not required.

I also understand, assuming there are no other connections into the sewer before the OP's property, that the section within the plot the OP is purchasing is not public sewer until it crosses the curtilage into the adjoining property (75).

Section62

Grumpy_chap said:

Section62 said:

Grumpy_chap said:

Looking at the plan, the scale is such that the existing extension is probably short of the existing sewer so it is possible that no previous build over agreement was required.

The OP will require a build over agreement for their new extension.

The requirement is for within 3m of a public sewer, so if the plan is accurate an agreement would have been required unless at the time the extension was built the pipe was not a public sewer.

Yes, I know.
And, given the scale of the plan, the extension is quite possibly 3 m away from the sewer as marked so still sufficiently short of the sewer that a build over agreement was not required.

Unless I've misunderstood something, the sewer (assuming the plan is accurate) is almost touching what appears to be the rear extension?

Grumpy_chap said:

I also understand, assuming there are no other connections into the sewer before the OP's property, that the section within the plot the OP is purchasing is not public sewer until it crosses the curtilage into the adjoining property (75).

It depends.

It is possible for a pipe to be a public sewer with only one property connected to it.  The 2011 mass adoption required that there were two properties connected, or that the pipe was within a different curtilage to the one connected property (reflecting what you understand) - but there are other ways drains become public sewers.

As a general rule, if connections and/or small diameter pipes are shown on the public sewer map it means someone has surveyed the pipes for some purpose in the recent past and confirmed they are public sewers - but the OP should still get confirmation of this if they go ahead with the purchase.

Another possibility here is that 75 and the other properties are upstream, and the flow in the pipe shown within this property is from top to bottom of the plan.

Grumpy_chap

Section62 said:

Grumpy_chap said:

Section62 said:

Grumpy_chap said:

Looking at the plan, the scale is such that the existing extension is probably short of the existing sewer so it is possible that no previous build over agreement was required.

The OP will require a build over agreement for their new extension.

The requirement is for within 3m of a public sewer, so if the plan is accurate an agreement would have been required unless at the time the extension was built the pipe was not a public sewer.

Yes, I know.
And, given the scale of the plan, the extension is quite possibly 3 m away from the sewer as marked so still sufficiently short of the sewer that a build over agreement was not required.

Unless I've misunderstood something, the sewer (assuming the plan is accurate) is almost touching what appears to be the rear extension?

I understand what you are saying but that image is extracted from GIS, which is indicative rather than accurate in the first place plus the thickness of that red line at that scale is about 3m wide.

Section62

Grumpy_chap said:

...

I understand what you are saying but that image is extracted from GIS, which is indicative rather than accurate in the first place plus the thickness of that red line at that scale is about 3m wide.

Completely agree with the indicative and accuracy point, but I don't think the red line would be as much as 3m.  The linewidths of this scale of OS mapping typically works out to something like 0.25 to 0.5m, and the red lines are not that much wider.

The image measuring tool I used gives the width of the red line as about 5 or 6 pixels.  If that represented 3m then that would be about 0.55m per pixel.

I'd measured the frontage width of the house at 75 pixels, and the highway width at 196.  Which would be about 41m and 108m respectively if the red line were as much as 3m.  Possible, but it seems unlikely the width of a terrace house would be 41m?

I worked on the basis the house is likely to be around 4 or maybe 5m wide (giving a plausible highway width of about 10m).

Which would mean most of the sewer in the rear garden of number 75 could possibly be within 3m of the OP's proposal, in addition to anything within the target property's curtilage.

(Edit: I was checking the measurements as the size of the rear garden isn't large, and the planners may baulk at reducing it further)