While the water and sewage bill is one on billing provider, it will stand to note this as it is still a bill. All water going down a faucet, or shower will go into to a grey water tank. This tank will then be used to provide water for greenery, and toilets. This is building wide, and I doubt the gray water tank will be sufficient to catch everything, but I will hope so. Water from the dishwasher, laundry, and the toilet will be considered as black water, and will go to the sewage. By saving some of the water demands for the toilets and greenery, it will reduce the bill, and make this a much better solution.