Desalination is pretty pricey at ~$2000 per acre foot, but desalination and wastewater recycling are your likely competition. Assuming of course that you're only going to sell this in drought-stricken areas. If you're aiming for wetter areas, you're competing with rain water, and its tough to beat free.

Could you give a walkthrough of how this works? I'm trying to get a better grasp on your prototype