Hm, my place is not that crazy, but it is also not that usual
There are lots of water war-types, and each kind of game got its rules. This is sometimes difficult to control. If you play a Shoot-down, where player wins, who is not wet, often will remain the problem that people may not identy themselves as "shooten" and out of game.
Therefore my suggestion for a water warfare: Just go out in winter, where lots of snow is everywhere

Give the teams time to build up they own safety-castle out of snow and then, play the shoot down game. You can play this just everywhere, because snow-walls could be built up whereever you like

. So, lots of places to hid, may difficult environmental circumstances(snowing, wind...) and all gunners covered with big, fat jackets, unable to run quickly...hahaha it would be great, I think. Then you just add some walky-talkies and let the fun begin ;D. And there is another big advantage! : A gunner, who is hit, will immediately or maximum after some minutes leave the field because it will be very cold in wet clothes

. So the shoot-down will played within the rules and only the quickest and most strategical teams win
I have not tried this yet, but I would immediately join such a warfare in winter...
You may have a problem with refilling/where to get the water from but I am sure there can be found a solution^^
Let's soak, xD