Waste Pipe Runs

[moby_wan]

I am just about to re-do my bathroom, I have just read that for a 32mm waste pipe it should not be more than 1.75m in length from trap to soil trunk, and if using a 38mm waste pipe you must not have a run greater than 2.3m. Why is this?

I wanted to move the sink, which would make the waste pipe around 2.7m long. Should I rethink the layout of my bathroom or doesn't it really matter?

Any help would be appreciated.

Thanks!

 

[chrishutt]

These figures are guidance in the Building Regulations Part H1 which you can download from the ODPM site. The intention is to avoid syphonage and other problems, but they are frequently ignored. Should you end up with a syphonage problem you can fit an anti-syphon trap.