Quality of Water

Water quality is not a single number but a composite assessment across several dimensions. Physical characteristics cover properties like temperature, turbidity (cloudiness), and colour. Chemical characteristics cover dissolved substances -- nutrient levels, dissolved oxygen, pH, and the presence of toxic chemicals or heavy metals. Biological characteristics cover the presence and health of the organisms living in or dependent on the water body, which are often the most sensitive early indicators of degrading quality. Aesthetic characteristics -- appearance and smell -- matter because they are what the public directly perceives and reacts to, even when they don't map precisely onto a measurable chemical parameter. A water body is judged healthy when all of these dimensions together support a rich, varied community o …