New house - land drainage problems in back garden

[New home buyer]

I bought a new build house last year, and since september I've been having problem with water streaming onto my newly laid extended patio from the lowest pints - where Ive dug borders out at the side. I have 2 pools of water on my patio when it rains After a discussion with the house builder it seems I have 3 land drains installed, which I wasn't aware about before I had my patio flag extended. My garden is on a gradient towards the house. The house buyers are saying that because I have put paving flag over one of the land drains its now redundant - so its my fault and responsibility, however the grass in front of the so called now redundant land drain is not water logged, its just at the sides where the 2 other lands drains are. Can anyone advise if building over a garden land drain by about 2 small flags can make it redundant?

[Tony McC]

The short answer is a very definite "no", and I think the longer answer involves these "builders" extracting urine.

Tell them you'll be bringing a drainage consultant in and, if it's found that their inadequate and/or shoddy work is the cause of the problem, you'll be on to your lawyer and the NHBC.

[AmazingGarden]

Given my experience of builders and developers 'putting in' drainage it is usually a pipe buried about 200mm below the ground with many falls and connected to nothing.
I spoke with the NHBC about drainage for a client and they told me that is only covers flooding up to 3m around the house and there are restrictions if you area clay soil.
Is it covered??

[Tony McC]

Is there a more useless, less effective, organisation than NHBC? The whole thing is a waste of food! A cosy club run by builders/developers for the benefit of builders/developers and to protect them against any claim from those pesky house buyers.