Flushed with, well, anything really

Tread lightly: Install a water-saving device

Some of the kit to help flush with less looks promising as one hopes they will be able to be tuned to still actually work. Flushing 2/3 times to clear the bowl kinda defeats the object.

But when it comes to the simple act of replacing a certain volume of water within the cistern, surely it is not beyond the wit of man to make something out of a second use item ( This may kick off some notions to find and share what works)?