Below is a diagram of the Rain/Bath Water Recycling System that has evolved over the last few years and has been largely proven with a demonstration unit built at my house.
There is also a system installed for extracting bath water through a hole in the wall and into the recycling water barrel. There are numerous ways of achieving this function and so I haven't shown any more detail here.
All I need now is the Grey Toilet Water add-on, which would require a temperature control system for the barrels plus local authority planning permission as a grey-water fixture.
The whole system has been built using off-the-shelf components for less than £200 (dependant on required features) and has been adapted for use with WiFi control for irrigation.
If anyone is interested in getting involved with the further development and installation of such systems then please contact me at: [email protected].