What diameter of John Quest pipe did you use,We used standard household John guest plumbing throughout our build, it’s much cheaper and more reliable than the red and blue pipes.
The push fit plastic fittings give a positive fit, and very easy to use.
I know this doesn’t answer your question but it may help if you have not decided yet.
What diameter of John Quest pipe did you use,
Also to OP, apologies, not wanting to high jack thread and go off on a different topic.
We used 15mm through out, for our water, the propex water heater had 12mm plastic tails which I pushed on 15mm to 12mm adapters, the water pump took 15mm tap connectors screwed straight on, then we used household taps and shower head.