Does anyone have a definitive answer about when toilets need to be vented? I always thought that if drain is in 100mm and laid at 1:60 grade then a toilet only needed venting if it was more than 6 m away from main drain.
I see a lot of houses where drainlayers put junctions on outside walls for AAVs when really the toilet doesn't need them.

Am I wrong?


Linkback: https://www.plumbers.nz/ask-plumbers-trade/43/toilet-venting-question/1917/

yeah that's what I thought Robbo, as long as everythings at 1:60 which is about 17mm per meter of fall, which is quite a bit really in my opinion.
The number of times I look at a plan and the architect wants vents on toilets which don't require it makes me laugh. I just read one which wants laundry tub run at 1:30 fall! Why?