As I mentioned in June we have been thinking hard about ways to further reduce our water usage. A recent sustainability action was to wind down the float screw in our toilet cisterns. What this means is that when the water refills after a flush it gets to about 3cm lower than it used to and the float device registers the cistern as 'full'.
Initial Time: about one minute per toilet.
Initial Cost: zero.
Ongoing time or cost commitment: zero.
Impact: Each flush is using 1-2L less water. Even on 'half flush' there is NO REDUCTION in how effective the flush is. Again I am a little embarrassed at how long it took us to do something so easy and effective.