Well, drinking valves sold for US$15 each over here, so I thought I'd try making one out of old bottles. I took out the stainless steel tube with balls from them and fastened them to PVC tubes just like Mark did with his system.

I thought for the balls to stop the water from flowing out was a completely sealed air-tight system, just like that inside a water bottle. So I put a few shut off valves on the water tank and sealed all the conectors with silicone. But still when I opened the valve from the tank to the system, water still shoots out from the side of the balls.

Anyone got any ideas?

What if I fill the water tank all the way to the top or use something to suck the air out of the water tank, to make a vacumn, would that work?