My daughter has a concreted patio area behind her house which has drains passing beneath it. It has a largish sagging area that sounds hollow and it’s fairly clear that something is undermining the patio.
She’s not sure who to call first. Her water company (just in case it’s a shared drain system), her buildings insurance company or a drain specialist?
My gut feeling is to do it in the order listed. If it’s *not* a shared drainage system, how likely is buildings insurance to help with the cost of repairs?
Does the drain serve properties other than her own? If it does, any part that carries other properties' drainage is the water company's responsibility. She is only responsible for drains that only serve her, on her land. See diagrams:
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The drainage authority (not necessarily the company she pays a bill to for water supply) will have a drainage map although, from looking at Thames Water's version of the map for a location I'm familiar with, it may not have all the private drains on it (my guess is TW add to their map whenever called out to a particular site, and if they haven't been out they don't have it recorded on their computer - for streets built pre-computerisation anyway).
It wouldn't hurt to call them and ask what records they have, if she doesn't already know. They may be able to come out and assess, even if the situation is unclear.
Is it possible the drains belong to somebody other than the drainage authority, eg a farm or other premises nearby? There would be legal paperwork for that.
Not sure, but I'd not expect the insurer to pay out for general maintenance. If there was an incident like a flood, they might pay out for the water damage, but not to repair something that should have been maintained.
It would likely need an investigation to find out the facts, irrespective of whether the insurance is paying or not.
Responsible, yes, but IME there is small print - along the lines of 'you do
*anything* to cause damage to our drain then all bets are off - you pay'. I've looked into this as I have a shared drain across my garden . . .
There should/could have been a search at the time of sale. I was advised of the drain, but not the location. My local authority holds the records for Sheffield - I went along to their offices and they lent me a laptop with the data - I took photos of the maps. Also rat runs if you're interested ;-)
They do but, again, IME, not shared drains.
I'm not sure of the best approach for the OP. If it were me I'd probably get one of those drain inspection people to take a look. One was done on this place before I bought it - about £200 IIRC but not sure as it was done by the seller. Looks *too* good to me.
Or, lift a section of the patio and see what's going on, and take it from there.
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