The quality of a water in terms of physical, chemical and biological parameters. The status of ‘good quality’ is dependent on the water’s intended use or purpose. For example, drinking water requires a much higher quality than for other purposes. For the natural environment, ‘good quality’ is that which meets the requirements of native flora and fauna, but may still not be safe for humans to drink. There are different water quality criteria for different manufacturing processes, or for agriculture.
Water quality is defined by water quality standards, specific to the intended water use. The relevant quality standards are defined by national or local regulation and industry sector guidelines. Where these are absent, international standards and guidelines should be applied (for example WHO Drinking Water Guidelines). For example, the manufacturing of sensitive products such as food, drinks, electronics and pharmaceuticals require higher quality standards compared to, say, mining or vehicle manufacturing.