Drains on houses covered by NHBC

Miffed_one

Hello there, I am hoping someone might have advice for me. I live in a new build house that is 5 years old and is covered by NHBC.  The drains have never been up to the job and periodically we have to get a plumber to unblock them. My downstairs toilet has had a raised water level for about 3 days and last night, my neighbour heard awful gurgling noises from her downstairs toilet and then it suddenly overflowed and went all over the floor. Her sink started spouting water from the plughole too.  She had to get British Gas to come and clear her part of the drain in her back garden, but the main drain is blocked and the building company who built the houses have called Dynarod to come out (by 6pm tonight). In the meantime, none of us in the houses in this corner can flush the toilet or run bath/shower water away etc.  The drains clearly can't cope, yet local authorities have agreed a medical centre can be built opposite and in principal, some flats near our houses.  Lockdown has probably also cause this blockage due to everybody being at home all day every day. 
Can anyone give advice on who we can go to in first instance to start investigating the drains serving our homes as something needs doing and it is unfair for us to have to periodically pay out for plumbers etc. if there is a building fault.  I gauge it wouldn't be the NHBC as I gather that another neighbour has tried speaking to them in the past and they weren't interested. Any help or advice will be gratefully received. Many thanks.

Ganga

You could contact the owners of the houses involved and club together to get the drains surveyed ,they put a camera down and will give you a report and i presume a video of the drains .If there is a design problem or a blockage caused by the builders at least you will have some concrete evidence to fight your case for a remedy 

Doozergirl

The water company are responsible for your shared drains.  Call them.  

I don't believe NHBC cover drains. My in laws house has subsided slightly and the drain directly outside their house broke because of land movement that was so visible that the road to the cul de sac had to be built up and resurfaced because it was becoming dangerous to drive up.   NHBC argued that the drain was the cause and the drains weren't covered.      Don't buy a house on landfill.  

weeg

Drains as far as your boundary line are covered by the NHBC. Beyond that they should be adopted. In Scotland (which is where I work) you have to get an agreement in principle before you start a development. They would do a capacity check on the system before giving permission. If the drains have been adopted (which they should have been) then the water company is responsible for the maintenance and that should be where you direct your complaint. It's been years since I had any dealings with english water companies, but I'm assuming they can't be wildly different from Scottish Water?

(and yes - lockdown is likely a significant factor)