The concentration or measure of a water quality characteristic that, based on present knowledge, does not result in any significant risk to the health of the consumer over a lifetime of consumption. Characteristics which indicate the safety of water in public health terms. These can include microbiological, physical, chemical and radiological criteria. Aesthetic Guideline Values. These include the concentration or measure of a water quality characteristic such as appearance, taste and odour that is associated with good water quality.
Some characteristics have both health and aesthetic guideline values.
Value This is the average of the test result values. They can be introduced into the water supply by rainfall washing debris including animal faeces into water bodies in the catchments. Monitoring is conducted of indicator organisms because they can be identified relatively rapidly, using simple and reliable test methods and are an indicator of the cleanliness of drinking water. These bacteria may come from the environment or from faecal contamination. Most of these bacteria can be killed by chlorine disinfection.