I've come to this forum as I've noticed it's a wealth of knowledge of all things rainwater harvesting. I work in water tank sales and often have to help customers with their tank fitout. Usually it's just advise on where to position their various inlet/outlets, as most people order a standard fitout, however sometimes people have unusual requirements that really require someone with plumbing knowledge to advise. That is not me but I'd like to learn more about rainwater harvesting and help out where I can also.
Anyway, so was wondering if anyone could help with this query. My client has a 150mm downpipe from his house that he wants to feed into his tank. His plans showed 100mm downpipes and 100mm overflow, which is normally fine. But since he increased his downpipe size we'd normally recommend increasing his overflow to match.
However, his tank also has stormwater detention fittings on it, and upgrading everything to 150mm will just make the setup too costly. So, I was going to suggest he consider using 2x 100mm overflows on the tank instead, one going straight to stormwater, the other with his OSD fittings connected to it.
So my questions are, 1) is that sound advice? and 2) how many 100mm overflows would actually be needed?
At first I thought 2x 100mm overflows would be more than enough, but a colleague informed me that the water flow through 2x 100mm pipes would be less than 1x 150mm pipes. I tried to find this flow rate calculator online, but the calculators coming up were a bit confusing
![Sad :(](./images/smilies/icon_sad.gif)
Can anyone please assist with this question?
Thanks!
Albri