Public Sewer within boundary

[Dr_Gonzo]

We're looking at purchasing a property and the drainage search has shown that there is a public sewer within the boundary (in the back garden). The map print-out is a bit unclear and doesn't show the exact position of the drain in relation to the house - it just shows a thick red line running through the back garden. On the map the sewer doesn't appear to run under the house but our solicitor thinks there's a chance that it may. The sewer runs through the back garden of the entire street and so if it's under ours it's under at least 10 other houses. Our solicitor is drafting a 'build over' agreement incase there is ever a problem in the future.

Has anyone else come across this and should we be concerned?

Also, we're hoping to extend a few metres into the back garden i.e. towards where the sewer appears to be. Is there anyway we can get a more accurate location of the sewer and if not, would the mere possibility of it being there jeopardise the possibility of having an extension?

Thanks,

The Doctor

[Dr_Gonzo]

The house next door has an extension of the size we would be after, so I'm guessing they would have probably encoutered any issues when that was built (althougth it looks 15+ years old). Does a drainage survey actually entail a site visit or do they just look up the records? Because the drainage records are a bit vague.

[Dr_Gonzo]

Skyedriver said:

I know its a house purchase so you don't know your "neighbours" but if you can have a look in the neighbours back gardens, you'll see a manhole cover somewhere, probably the end houses but not necessarily. A tall stick so you can see it (a ranging rod if you can get one) and you will get an approximation of the line, by joining the dots although the cover could well be a little offset from the actual pipe run.
A building over agreement is needed if you are "building over" the sewer but if the depth of the sewer is say 2metres then your building over if you are 1.999m away.
The likelyhood is that you won't have a problem if the sewer needs digging up in the future because of a problem, the water authority would likely carry out a diversion instead but you cannot guarantee that if there is no where to divert. Worse case scenario is they can simply demolish your extension....

The garden of the house to the right of the property has been completely hard paved so either they've paved over it; it's in their garage; or there isn't one. The house to the left, the last house on the row, also doesn't appear to have a man-hole in it. Also, several houses to the right have also paved their entire garden, and as far as I can see there's no man-hole covers in any of the gardens. So now I'm a bit