Properties of different waters used in EW production.

Properties (hardness, Ca, Mg concentration, and pH) of starting water used to produce EW are presented in Table 1. Considering US geological survey report (USGS, 2012), the both TW and UW can be categorized as soft water. Water hardness is primarily the amount of calcium and magnesium, and as a lesser extent, iron in water. Water hardness in most groundwater is naturally occurring from weathering of limestone, sedimentary rock and calcium bearing minerals. However, TW used herein was harder than UW. This is a paradoxes observation that is hard to explain.