I have a project planning to use 100% non- potable water for irrigation.They are planning on doing this through collecting rain water. It rains a good bit in the area of the project but sometimes there will be 1 dry month in the summer. Would they be able to use potable water that month (I told them probably not, then not 100%). Is the only option here to get water that month from a public agency in the area that supplies treated non-potable water for irrigation?