Thank you.
Humm, I wouldn't use too much of grey water for your garden, and even if you use basic eco-soap: It is not because a detergent is eco-friendly that it does not have chemical properties while it is active... (Being eco-friendly means that a compound degrades readily and the degradation products are harmless for nature).

I have a garden too , and will probably get active on this with the return of warmer days. You should also follow my friend Delphine (@Delph-in-holland), she is a gardener and very much into developing and using nature-friendly solutions to gardener problems!

For example, we rent a larger common garden together, and we are testing / using permaculture techniques.