Hi Steven, Yes it is safer to use separated grey water than raw sewage, that's a good start… but
bear in mind that if you are feeding food plants, you need to be happy with the ingredients going into your irrigation mix. What are the ingredients in your
shampoo,
soap, washing detergents, cosmetics etc.? Make sure that you are happy to put these on your vegetables.
Fruit and nut trees similarly.
If you are in an arid climate, then it may be well worth using the irrigation water. If you're not, then have a longer think about it. What is the practical advantage of using the grey water for irrigation? If it's simply to say that you're reusing it, then that isn't necessarily reason enough.
One option to lengthen the chain of connection between source and food plants is to plant comfrey… but I'm repeating my last post here.
Summary: it's safe if the ingredients going into your grey water are safe. Paradoxically,
urine would be cleaner from a toxicological perspective, and much higher in nutrients.
Does what I've said so far help at all?