create a business model for my prototype

A water saving idea that has been researched and requires marketing. I require ideas to sell the model to local authorities that are besieged with water shortage.
My idea is existing gray water harvesting, only this time we clean bath/shower grey water and use it to flush the toilet, instead of using potable water to flush, as is the case.
I would provide the rest of the information once I realise there is relevant assistance here.