Potable water vs. Non-potable water

The water needed for the entire building could hardly be provided by rainwater only, also if rain doesn't fall or drought continues for a long time, we will have a problem. Here is an idea to overcome this issue.

Potable water is used for preparing food or beverages for human consumption, for washing dishes and utensils that are used to prepare or consume food or beverages, for bathing, or for any other purpose that might result in the ingestion of water or its contact with the skin.
Non-potable water is not appropriate for human consumption, it can be used in a myriad of other applications, such as doing laundry, toilet and urinal flushing and cooling tower make up water.
From these concepts is possible to see how convenient would it be to have a separate systems inside the building for potable and non-potable purposes. Our propose is to collect water from the rain and humidity in air and give it a proper treatment to make it drinkable, at the same time we will use the waste water from the building after a proper treatment for non-potable means, having a separate distribution system for potable and non-potable water inside the building. This way the water that we would need to collect from the rain will be considerable reduced and the process treatment will be easier in both cases.