I need a simple design for creating a gravity feed water supply valve for a cage full of ducks, they love to waste water but 5 gallons seems to supply them for a day, I have the 5 gallon jug sitting on top of the cage but it operates by siphon, which is unrelyable. The siphon stops or trash clogs it. The local feed supply has one for $31.00 but I plainly am too cheep to go that route. Anybody got a working design? The one at the store has a caged float which travels upward to stop the flow when the container is full. Space is at a premium in this case so a toilet valve will not work.