Should we be responsible for Stormwater Attenuation Tank?

Daisychain1214

My partner and I are currently in the process of purchasing a new build property. Upon looking at the plan we noticed that there was a 'tank' marked out under the part of our driveway that is shared with one other property next door. The salesperson selling us the house had no idea what it was and upon querying it with the builder, came back to us and said it was a stormwater attenuation tank. It was explained that it was there to basically protect the estate from a 1 in 100 year storm event so would likely never need to be used. 

We are now being told that, along with the house next door, we are responsible for the maintenence and upkeep of this tank. Considering this tank is there to serve and benefit the whole estate of more than 100 houses, is it actually reasonable that we are being told this or should it be down to either the water company as it connects to the drains and sewers, or maintenence company that we will be paying a monthly fee to? If it was there to just benefit our 2 houses then obviously that would seem reasonable but it's not. If it wasn't under our driveway, it would have to be the responsibility of someone else and not just our 2 houses, so is this fair? 

user1977

What exactly have you been told and by whom? I'd expect it to be a cost you'd be sharing with everybody in the estate, so in that sense you are responsible (along with your neighbour and everybody else). But as it's under your driveway there will presumably be additional conditions that you're not to e.g. build or plant over it.

RelievedSheff

It won't be adopted by the water authority if it is under a private driveway so it should come under the remit of the estate management company.

FreeBear

Depends on the size - If this stormwater attenuation tank consists of a handful of SUDS crates, then the only thing you need worry about is the maximum vehicle weight you can drive/park on top.

In terms of maintenance, there is virtually nothing you can do as they should be buried at least 500mm down and may well have a substantial layer of concrete over the top. If there is any way to gain access for cleaning, then there would be an inspection cover directly above it.

As this is a new build, it won't need any maintenance work for at least 25 years, maybe even 50. By that time, it will be someone else's problem and who is responsible will be long forgotten - Quite likely, the existence of the SUDS crates will be forgotten too. It would be well worth asking the builders about the size and construction of this stormwater attenuation tank and get hold of a copy of any drawings. Keep them stored with your home information pack somewhere safe. Should any work need doing to it, you (or subsequent owner) will have some clue as to size, location, and construction.

weeg

I imagine every house/ pair of houses on the estate will have one. It is just there to benefit your two houses.

Basically, water companies don't accept stormwater runoff to combime (or foul) sewers under most circumstances for new builds. So these tanks are installed either to hold the water until it can soak in to the ground, or to hold it temporarily so that downstream pipes aren't overwhelmed, and allow it to flow away more slowly, either to a water course or to the freshwater system.

As for maintenance, basically keep your gutters clear as you usually would. They shouldn't need any regular maintenance. They di silt up eventually, but that's a long, long way in the future.

tacpot12

I would agree with what weeg has said about it probably only serving the two houses, and not the whole estate, unless you have information to the contrary. I would also endorse the advice from FreeBear.