We've got a water butt in the garden which we use for watering plants and stuff when we're not away on holiday but there are loads of other saving water tips that seem obvious when you see then but might not occur to you otherwise. For example, ever since we got a dishwasher, we make sure we properly scrape the plates off into the bin rather than running the pre-wash programme because that means more water usage, never mind the extra electricity.
It used to be conventional wisdom that drawing a bath used more water than having a quick shower but now days with power showers it isn't always the case. Don't believe me? Next time you have a long and luxuriating shower, pop the plug in and see how full the bath gets by the time you've finished. Talking about sanitation, when we had out bathrooms refitted, we made sure we had cisterns (close coupled in both instances) that have dual flush functions- a half flush for shifting wees or a full flush for more serious issues. Even then, we don't flush wees during the night because it's a waste of water and the boiler is right next to Ned's bedroom and we don't want to wake him up.
I know it's small fry considering the amount of water that's lost in pipe leakage by the big water companies every day but if we all do every little thing we can, it can make an difference.