For other people who use a nipple type or other trigger type watering tank that are prone to sticking or leaking and you want to limit the possibility of flooding the coop you can attach a fill hose to the tank and put a sprinkler (irrigation) timer on it so it only comes on for a few minutes...
Very Simple fix I use the same waterer with my birds.
Just get a float fill valve and drill a hole in the side of the waterer and adjust the float valve to the height you want. I attach mine directly to a hose. In your case just connect it to your tank with a hose.