I filled the water the water tank a few days ago so I could test the tank for leaks prior to the spray insulation being applied.
I am please to say the cabin side is leak free.
However there is still a leak which is finding its way into the chain locker of all places. I had hoped not to have to go in the tank and do more welding, but it seems its going to have to be at some point. I hasten to add that the weld's that's leaking are NOT mine, but also in fairness the space I am using was not originally intended to be an integral tank. I suppose I can't moan.
Another option would be to drop the level of the overflow so it didn't reach the level of the leak. But this would be cheating and would probably cost 100L of capacity.