Using Grey Water on the Garden - Does Anyone Else Do This?

Where we live in Australia it seems that as far as rain is concerned it is either feast - see photo - this is what happens in heavy rains - our lower garden gets flooded when the creek overflows across the foot of the gardens which are on a steep block of land. Or famine - witness the bushfires of October 2013 due to drought and high winds. So, with thoughts of a better way to water the garden or at least conserve our rainwater tanks for bushfire season - I am experimenting with using our grey water, our used vegie water and so on for the garden. I am starting small: For instance, when you wash your hands which happens a lot during the course of the day - did you realise that while waiting for the hot water to reach temperature before plunging your hands under the tap - and whilst washing your hands and leaving the tap running while doing so - that you easily waste between 2 - 5 litres of water down the drain? I am now keeping a 5 litre watering can by the sink to catch the water that would otherwise go down the drain. During the course of one day - just by capturing this water, I collected about 22 litres of water! Then there is the vegie water that we boil our veg in for dinner. I poured this off into 2 litre plastic milk cartons (wait for it to cool down first) rather than down the sink. This saved another 2 litres of water in one day. Today I put a 12 litre bucket under the shower while the water reached temperature and even left it there whilst I showered - another 10 litres collected! Goodness, that is a lot of wasted water going down the drain on a regular basis that would benefit my garden. I think I will keep going with this and see how it goes. Does anyone else have any good tips on saving/capturing water for the garden. We already have two very large rainwater tanks (a council requirement as we are in high bush fire risk area) but if we get no rain - then they are of no help! Thanks all.