As I mentioned in my post above, gray water can be used in some areas, but there are significant restrictions, including ones that outlaw indiscriminate dumping of many RV gray water tanks.
Below are two links. The first is to a PDF that outlines what is permitted and what is not in my home state, New Mexico. Note, among other things, that the law is designed so that more local restrictions can override it.
The second link below is a standard webpage that includes a chart comparing restrictions on gray water use across several of the states here in the southwest.
http://www.nmenv.state.nm.us/P2/documents/Gray_Water.pdfhttp://www.nmenv.state.nm.us/fod/LiquidWaste/graywater.htmlLynn