Whilst I applaud the idea - any greywater waste should be diverted straight to the garden and not stored for more than 24 Hours
Andy as a licensed plumber mate be very careful of what and where you use greywater waste ....I got visions of Typhoid, Cholera and Diptheria outbreaks springing up all over Australia
straight onto the lawn the laundry water is going now, the water from the kids/main shower goes onto the garden, this will eventually go onto the lawn as well.
I see no need to retain grey water, just move the disbursement hose around so all the lawn/trees etc. get the benefit. Just don't leave it in one spot.
My parents last property was around 40 acres...plumbing from the kitchen, bathroom sink and shower went straight out into around 15 metres of ag pipe...which fed quite a lot of plants...completely against any council regs, but considering no-one ever inspected it...
Something about living on tank water for 18 years makes you fairly water conscious...
I siphon my laundry water out to my plants after the addition of a splash of seasol/maxicrop. At Mums the washing water is diverted to 2 drums, a splash of seasol added and then gravity fed throughout the garden (including vegies) over 12-24 hrs.
The surfactant(detergent) level in the water is not a big issue, it is the Phosphorus and Salt level you need to watch. After all, Wettasoil is pure detergent and helps prevent water lockout in soils and potting mixes.
And bad bugs in the grey water and not putting it on your vegies? Oh please. Any horticulturist can tell you what awful pathogens and nasties are in ordinary soil and compost.
This is the info given to licenced plumbers in sydney about Grey Water. I get asked alot to run pipes direct to the lawn but I am unable to do it untreated.