I apologise for the length of this message but
I am really worried as the private landlord of the house next door has concreted over most of his back garden- about 7m x 5m. There is a grass lawn at the bottom of about 3m x 5m. He has laid a thickness of about 3 inches over the whole area - and used broken flags to create a small upright round the whole thing - level with the height of the concrete on the far side. The lower edge next to our garden is made up of an old concrete wall which is about 4" above the patio he has laid but has gaps in between the flags/wall and he has left a gap at the corner level with our flower bed.
The problem is that we are lower down than he is by about 3-4ft and do get surface water run off as his garden has a slight slope down towards ours. We have already built 2 raised beds and put in a trench below these.
The patio he has laid has no drainage and when I asked his builder about the water running into our garden and flooding it I was told it's only rain. I lost my temper and told him I would take legal action if they damaged our garden which they found highly amusing. The concrete is like porridge and so rough that the new tenant who moved in the day after is horrified and wants to put a screed on top to stop her 3 kids from hurting themselves, if they fell on it now it would take off a lot of skin.
The problems we have are that we are on heavy clay, there is nowhere for the water to go once it comes into our garden; the house behind us is 20ft lower down - the top of his garage roof is level with the top of our back fence panel. From the end of the patio to the bottom of the garden the boundary is a large hedge. So we don't really have any room/options to put in any drainage, that I can see.
From past experiences in dealing with him I know he will ignore any requests we make to put this right.
Any help/advice would be greatly appreciated.
Thank you
Chrissy