manhole cover under extension!

28 Oct 2009
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United Kingdom
hi any advice please,
our house had an extension to the rear built 30 year ago with building and planning permission. on speaking to neighbours the manhole is under the extension. although the drains are not blocked now, i dont want to be faced with an emergency in the future. rang the local council to enquire about the drain plans for the property but as it was built over 60 years ago they told me to ring the local water authourity which i did. they informed me they dont have individual drainage plans but advised the drains run underneath the property to the main sewer at the front of the house. on speaking to neighbours they are adamant the drains link to the main sewer at the back of the house as they had probs years ago and had to repair and join a dislodged pipe to the main drain. they also tell me that the manhole is 8 foot deep. so looks like we are going to have a big job on our hands sorting it all out. can anyone advise how i can find out for definite where the main sewer is. thanks
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There are specialist guys that can trace it but very expensive, I wouldn't worry about if there's been no problems to date.
Try looking a a good sample on neighbour's houses and clearly measure the location of the manholes.

See if you get any correlation and if that would point you to where the manhole was.

As DIA says ignore it until you have a problem.

If you really want to throw money at it then dig down in the garden and install a new manhole there.

thanks doitall and agile. the neighbours either side have lived there for 40 years.they say the manhole is definite under extension and previous owner complained of smell of diesel coming from the hidden manhole. would there be a way of clearing the manhole{drains} if there was a blockage, from the outside waste water{surface} drain that must be around 15 foot from the mystery manhole.i have thought about getting a firm to put a camera down but would this show me beyond the manhole towards the main sewer outside the property to show if it runs to the front or back of property. thanks again for the replies.
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If the houses were built together then all will be similar.

So see what how the neighbours are routed.


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