How much does additional drain work add to cost of an extension?

[sugarhoops]

We've just put planning in for an extension - goes right over the top of drains, an access point (where the neighbours drainage also joins ours to go out to the road - therefore I think classified as a shared drain so water authorities need to be involved), plus need to move 2 x outlet drains (kitchen sink, downstairs toilet).

Sorry for my completely non-technical terms, no idea when it comes to drains, but just wondering what sort of figure we could be looking at in terms of cost of moving / sorting all the above?

£2k? £5k? or more ?

It was about a grand for us, plus about £400 to Thames Water. Not a deal breaker. We moved a manhole and a surface run off drain.

Ok thanks mummytomog - sounds similar to ours in that we will need to get water authority involved. I just feel so frustrated sometimes in that no-body seems to be able to give us rough costs for certain things in a build - its all abit cloak and dagger really! Mumsnet has been my only good source of information so far!