What does "water quality" mean?

Introduction In January 2005, the Jordan Valley Water Conservancy District (JVWCD), a public agency that supplies water to much of Salt Lake County, Utah, drilled an exploratory test well. The well proved to be reasonably productive, and chemical analyses of the water showed that it met all primary water-quality maximum contaminant levels (MCLs) and most secondary standards for drinking water as established by the Utah Division of Drinking Water. But despite this, the water was not considered to be of sufficient quality for Salt Lake County’s public water supply. The problem was that the water’s temperature, as high as 83 F (28 C), made it too warm for the taste of JVWCD’s customers. Much of the ground water available in the Jordan Valley is recharged from snowmelt originating in the nearby Wasatch Range and is relatively cold (Thiros and Manning 2004). Typical JVWCD water supplies have temperatures ranging from 50 F to 60 F (10 C to 15 C). However, upwelling hydrothermal waters associated with faulting that formed the Jordan Valley were apparently affecting the test well, causing the unusually warm temperature. When people turn on the ‘‘cold’’ water tap, they expect the water to be cool, not warm. The quality of the water from the new test well, therefore, was too poor to be put into distribution. The term ‘‘water quality’’ has been in general use for the last hundred years or so. But to many people, this term is somewhat vague and poorly defined. Does ‘‘good’’ water quality mean the absence of man-made or natural contaminants? Does it mean that such contaminants may be present, but that the concentrations are below MCLs? Or, as in the example just given, does it mean that it simply satisfies the expectations (cold vs. warm) of the people drinking it? In other words, does water quality depend on the characteristics of the water itself, or is it merely what people happen to like?