No.1 U.K. Professional Trade Forum, Plumbing, Gas, Electric, Tiling and Joinery Forum

Hi,
I have a space of around 500mm between house wall and boundary to install both surface and foul 110mm drains at side of new build. The foul drain is deeper than the surface water drain. As the foul drain has more take offs for toilets etc I was planning on putting it closest to the house. Is there a minimum distance that the two runs need to be apart. I reckon there will be approx. 300mm of difference between the invert levels and assume the surface cannot go directly above the foul pipe. I am not allowed to use a combined system.
Any help or advice much appreciated.

Hi Drew and welcome to the forum, drainage isn't my strong point but know others will be able to advise.

Hi & welcome.
Not my subject either really, covered it in college once but i dont do anything that gets me dirty as i stick to gas lol

i did always think you couldnt go closer to foundations than 500mm though so that one puzzles me!!!
what local authority is it as i know Kent and the Home counties have tighter rules due to flooding?

Redsaw,
I am in Scotland so probably different rules. I had a previous build where the pipe ran quite close to the external wall but not sure of exact measurement