New extension - soakaways required? - Extension soakaway

[Himore]

Hi. Hopefully someone out there can offer some advice.

I have some builders in at the moment, hopefully completing an extension in the New Year (new garage, tile roof "garden room" at back of house, and utility room to the side).

On the plans, it clearly stated that the rainwater for the extension should run to a soakaway(s) position at the back of the house down the garden. The builder fitted the guttering this week, and has fed it all into the main sewerage waste pipe, saying that soakaways are a bad idea (flooding in the garden), and the building regs won't pick up on it anyway. He has said if they do say it's necessary for the completion cert then they will dig the soakaways though.

At the moment I'm paying over £100/year to the waterboard for removal of surface water, as the main property still has the guttering going into the drains. They say I won't get any exception on paying this fee, unless ALL my drains run to a soakaway.

So what should I do?
a) insist the builders make the soakaway, and run the extension drainage into this?
b) let the building inspector decide, and knock an amount off the builder's invoice if they don't have to dig a soakaway?

Your advice would be gratefully accepted.

[Tony McC]

Soakaways are the preferred option for all newly-installed surface water drainage schemes unless there are specific reasons not to do so. It all part of the SUDS business - Sustainable Urban Drainage Schemes/Systems.

There is a reasonable chance that if your builder connects up to existing SW the BCO will accept it as fait accomplit, but when it comes to knocking money off the bill: there's not a great deal of difference in cost between installing a simple, one-house soakaway and making a new connection to an existing system.

Personally, if you have well-drained ground, the soakaway is a better option, environmentally speaking.