I wonder if this is selling in Singapore. Now, you can conserve your water by using Saturator water gun. It fires in repetition using motor. They called it Automatic Motorized Shooting. And not only that, you can have water clips (or Magazine) as refill, just like a real gun.
The only problem is that you will need battery to operate it. But hey, it is motorized. You will not need to waste time pumping your water gun or finding water source to refill.
Too bad, the StreetWar in Singapore has been canceled due to some licensing and issue with our Police Force. If not, many of the contestants might be ordering these “weapons” to win the war 
.
There are a few models like Saturator AK47, SIG Sauer and Disruptor. Here is the video.
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