We are in the worst drought since records started being kept.
That sounds awfully familiar, edgar.
Good luck, I hope your drought doesn't go on for as long as ours here.
I know you're more interested in your trees than the survival of your garden, but I'm posting this information (to add to dadpad's & Butrflynet's posts) on grey water for anyone else who might be interested. Particularly the recommendations on cleaners & detergents in grey water. We found we had to change ours to brands which were more user friendly.
Practical suggestions for safe garden use
* Use a coarse filter to reduce the amounts of solids in your greywater. Otherwise, your plants will suffer from clogged soil.
* Ingredients in cleaners and detergents that can harm or kill plants include total salts, sodium, chloride and boron. Check product labels carefully.
* Evidence suggests that microbes from greywater have higher survival rates on the topsoil. All irrigation should be located sub-soil. Never hose, spray or mist untreated greywater.
* You may need to reduce the amount of fertiliser you use (note that native plants don’t like nutrients – plant selection could be critical for nutrients and soil moisture levels). Consult with your local nursery for further information.
* Regularly water your garden with fresh water to help prevent the build-up of salts in your soil.
In Victoria (Oz) a new medical condition called "bucket back" was identified during the worst of our drought, from carting all those buckets of grey water from house to garden. I think I might have had it for a while there.
I now have acquired something like 10 buckets, from some extremely dry summers.