Water blending: calculating quality and costs

As water costs skyrocket and availability diminishes, there has been a resurgence in the search for new water sources, including well water and recycled water. In some cases, two sources of water are available and there is an option to blend a high value/high quality water with a lower priced/lower quality water. In this situation, how do you know how much of the "bad water" can be blended with the "good water" without causing serious management problems?

The answer is…