Surface water pipe running under neighbours house

[apt]

Laying a new pipe from our new patio into a triple junction which I have put into the existing underground pipe. However Whilst doing this I was inqusitive to know where the pipes ran. It seems to go under my neighbours extension they had done some years ago. Obviously building inspector approved this, but would it still be in use on their side or do you think they have had that bit blocked off? As this is just surface water piping I can't see what it would be collecting from their end.

I also don't know where this piping ends up (on our side of the fence. We have several man holes/inspection chambers. Looking in them they all seem to be for the toilet/shower etc waste. I cannot see any manhole covers for surface water. We have a stream at the back of the house, could the pipes be running into that?

[Tony McC]

We can't see your site, so we can't do anything other than guess. There's some guidance on the main website about how drainage sytems can be 'tracked' using dye or radio transmissions - have a read of that.

If the pipe under the neighbour's has been sealed, it will back up. If water is flowing through it without hindrance, then it is still "live". Drain tracing dye will reveal whether any of the pipework is outfalling to the stream.

[matt h]

have encountered several cases similar to this if the pipes run under next doofr it is likely they have an inspection chamber in their extension, as it would have been cheaper to build over existing drains than to reroute them. Why not ask them politely .to see if it flows through. Can cause problem if they have actually covered the inspection cover though. Had one customer who had patio built and flagged over inspection cover and drains were blocked by intruisive pine roots... he only realised when his missus complained about some creepy looking stuff comin up the bog !:D

[matt h]

ps dont assume building was approved:rock:

[apt]

Thanks for the replies. Lol about the roots. Nice scratching post for the old piles.

I'm aware they did have building inspectors around for the footings. Apparently they had to dig very deep due to the big oak trees we have behind the back gardens.

For what its worth the pipe did have a good 2 inch movement when I dug around our side of it (which exposed a meter of pipe). Is this normal?

[matt h]

should be bedded in. with ground movement and such collars get broke. could be open jointed, but without seeing your site cant comment.Is there any sign of water seepage? Could be that their end is free or mortar joint washed out... Have you checked which direction the pipe flow is yet? could be its one of their old pipes coming to your side and isnt live?