Chapter 5: Water Treatment

The primary objective of potable water treatment is to provide water that is of appropriate quality for the intended use at a reasonable cost. Potable water should be microbiologically and chemically safe and aesthetically acceptable to the consumer. In addition, the water quality may be adjusted to avoid or minimise undesirable effects such as plumbosolvency, corrosion, lime-scale deposits or biological growth. The quality of water is defined in terms of individual physical, chemical and biological parameters, and these parameters are used for both operational and regulatory purposes. For the latter, they form the basis of legal standards that define the health risks and palatability of drinking water, and this will be discussed in detail in Section 5.2. These drinking water quality standards are set by national governments to protect human health in their countries. Most water quality parameters are unambiguous in that they refer to specific chemicals (e.g. NO₃, Pb, Mn), particular micro-organisms (e.g. E.coli) or physical properties (e.g. temperature, electrical conductivity), but others are surrogate values which give a general indication of water quality that can be conveniently measured manually on-site or by on-line instrumentation (e.g. turbidity, colour, pH).