Oscar and I went to a local nursery and got lots of lovely plants for our water recycling botanical cell. They are all in and so far none have keeled over dead. We are now flushing the toilet with water that has been used for our shower and then filtered through the gravel and peat moss to the well at the end of this cell. A pump sucks it up and sends it to the loo. When the washing machine and kitchen sink go in, grey water from there will also go into the cell.
To be honest, the water is a bit smelly when agitated at the moment and it is black from the peat moss but apparently (and here I am really, really hoping theory becomes reality) this is normal and it should get better and better as the plants become established and the mini-ecosystem that cleans the water starts to evolve. We always have the tank water option if it hasn't worked in about a year or so.