In the film Nowhere to run there is a scene where two propane tanks are on fire or being heated up,they solve this problem by pushing over a wooden water tower using a jcb, the water then creates a small wave and goes over the tanks and instantly cools them.

Is this possible for it to actully happen? The things im not sure about is the instant cooling and the wave that was directed in only 1 direction,

you can try this yourself!

not with propane though!

Just put some hot water in an empty pop bottle, and run it under the cold tap for a half a minute, is the liquid inside still hot?

I presume this wave puts out the fire then? if the tanks are no longer being heated then they would be unlikely to explode, unlikely is not impossible however!