Hopefully an easy question, but I couldn't find an answer via Google.
How far should a toilet overflow pipe extend from an outside wall? (to avoid any overflow coming into contact with the wall)
I ask because our toilet was overflowing and I finally noticed when I saw mould on the inside wall - dammit. I think I was a bit unlucky due to the prevailing wind direction but wondered what others thought.
Cheers PJ
Well, measure the height of the overflow above the ground and the diameter of the pipe itself, and the angle that said pipe subtends to the wall. Then calculate the maximum volume of water per minute which could emerge from the pipe, divide that by the viscosity of the water and multiply by the square-root of the maximum wind velocity that the pipe will be exposed to, then....
...on second thoughts, just extend it about 6" like everyone else.
TBH it shouldn't really matter if some emerging water does contact the wall, because the pipe is only there for emergencies (ie to prevent a flood if something fails in the cistern), and if you do ever see water coming out, then it indicates that immediate action is required - doesn't it?!
David
Presumably a slow drip type overflow rather than a full flow failed ball valve type. 6" is enough but it needs to slope down so that drip type overflows don't run back down the pipe and into the wall. I think there are regulations now about having a T piece on the end of the overflow, partly to reduce airflow in/out of the pipe and presumably to mitigate the shoddy installation of uphill pipes.
Change the siphon for a new one with an internal overflow.
I'm not keen on those, though we have 2 toilet water tanks with that system in. Having worked in an industry that always used belt and braces and something else to back it up, what happens if young child comes along and uses all of the roll of toilet paper and the ball valve starts to leak? This actually happened when I was site supervisor at the local primary school. Thankfully the toilets were updated just before I left the job, so that problem never occurred. A blockage was a regular event though.
Just wondering, as we had the g daughters up for 2 weeks and went through a whole rake of t rolls.
Dave
Thanks all. As suggested it looks like the small flow of water combined with the pipe being horizontal is what allowed it back onto the wall. I'll stick a tee on the end.
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