Ok chucklefucks i hope you like homebrew!

We currently have a set of maze tanks down the side of the house. They fill up pretty rapidly, so when we're looking at good rainfall i swap the overflow out to an old greywater wheeliebin to pump to other tanks / use in garden. You can see the temp setup from yesterday's rain - the flow to stormwater is on the right, the temp plugged vinidex to the bin on the left

I'm looking to make this process easier than plugging/unplugging plumbing, so was planning on putting in a T with the side to an outlet I can clip an18mm hose onto for the bin, and the down with a ball valve underneath (then leading to the stormwater to cut over to binfill vs stormwater as opposed to my current screw/unscrew/can't curve the poly that much so it takes up half the pathway. Simples, yes?

But then i had An Idea. The top links between the tanks are a PITA. Always dribbling, don't feed through very much, would be a gigantic pain to redo as they're very tight and the bottom link is cemented...so what if i tied in the bottom link (white pipe at the bottom left) at a slightly lower height than that top overflow, which would stop the top links hitting regular capacity, but be able to use them during high flood.

So: standpipe from bottom linking pipe to tie into the top overflow, then work in a tee and a valve so I can cut over the flow from stormwater to bin....workable?