Water Quality - an overview.
An overview of the key aspects of individual parameters for water analysis are derived from the NHMRC - Australian Drinking Water Guidelines (ADWG). There are two ADWG value parameters established which are Health related and Aesthetic. 'The Australian Drinking Water Guideline (ADWG) for Health value for each chemical is the concentration that, based on present knowledge, does not result in any significant risk to the health of the consumer over a lifetime of consumption and is consistent with water of good quality'. The health values are very conservative and a range of safety factors are considered erring on the side of safety. 'No Health guideline' refers to insufficient data to set a guideline value based on health considerations'. An aesthetic guideline value is the concentration or measure of a water quality characteristic that is associated with acceptability of water to the consumer, including colour, taste and odour.
Qld Health recommend drinking treated, town (reticulated) water if available.
E. coli (MPN/100mL or cfu/100mL) ADWG Health is <1cfu/100mL or Not Detected (ND).
E. coli is the most common Thermotolerant coliform present in faeces and is used as an indicator for many enteric pathogens. Thermotolerant coliforms includes Faecal coliforms, however, not every Thermotolerant is a faecal coliform.
The new Aust. Std. is AS 4276.5:2019 (E.coli, Coliforms and Thermotolerant coliforms, now in the one standard):
AS 4276.5:2019 allows incubation at 36°C for E.coli and Total coliforms, 44° for Thermotolerant coliforms and E. coli.
Heavy metals, organic chemicals including halogenated organics; specific industries can be associated with specific types of contaminants (eg arsenic and copper associated with wood preserving, cadmium and chromium with electroplating and chromium with leather tanning)
Mine wastes from pyrites tailings can release and transport metals such as aluminium, iron and manganese; other naturally occurring metals such as cadmium and copper can also be leached; arsenic can be associated with old goldfield areas.
Lead and zinc from roads, turbidity, colour, petrol/oil products.
Aluminium (Al mg/L). ADWG Aesthetic is 0.2 mg/L (No Health guideline value). Al occurs in water from natural leaching, and also used as floculants in town water treatment.
Copper (Cu mg/L). ADWG Health is 2 mg/L. Aesthetic is 1 mg/L. From corrosion of pipes/fittings by salt, low pH water. The taste threshold for copper is in the range 1–5 mg/L, depending on the water purity. Concentrations above 1 mg/L may cause blue or green stains on sanitary ware. Such stains may also be due to slowly leaking taps, where copper corrosion occurs over a long time, and are not necessarily due to high concentrations of copper in drinking water.
Cadmium (Cd mg/L). ADWG Health is 0.002 mg/L. Indicates industrial or agricultural contamination. Contamination of drinking-water may occur as a result of the presence of Cd as an impurity in the zinc of galvanized pipes or cadmium-containing solders in fittings, water heaters, water coolers and taps. Cd is mostly available in food.
Nickel (Ni mg/L). ADWG Health is 0.02 mg/L. Concentrations usually very low; but up to 0.5 mg/L reported after
prolonged contact of water with nickel-plated fittings. Nickel is used in the electroplating industry and in alloys used in the chemical, marine, nuclear and aerospace industries. Nickel is present in many foods. Highest concentrations occur in cocoa, soy beans and some cereals.
Chromium (Cr as Cr(VI) mg/L). ADWG Health is 0.05 mg/L. If the concentration of total chromium exceeds this value then a separate analysis for hexavalent chromium should be undertaken. From industrial/agricultural contamination of raw water or corrosion of materials in distribution system/plumbing. If guideline value exceeded, analyse for hexavalent chromium.
Arsenic (As mg/L). ADWG Health is 0.01 mg/L. From natural sources and mining/industrial/agricultural wastes. In some parts of Australia, concentrations of naturally occurring elements such as arsenic, fluoride and uranium, or nitrates from agricultural land uses, may exceed safe levels.
Mercury (Hg mg/L). ADWG Health is 0.001 mg/L. Mercury is used widely in electrical components including cells, lamps, arc rectifiers and switches. It is also used in dental amalgams, fungicides, antiseptics, preservatives and pharmaceuticals. Food is the main route of exposure, with highest concentrations found in fish and fish products.
Lead (Pb mg/L). ADWG Health is 0.01 mg/L. Lead can be present in drinking water as a result of dissolution from natural sources, or from household plumbing systems containing lead. These may include lead in pipes, or in solder used to seal joints. The amount of lead dissolved will depend on a number of factors including pH, water hardness and the standing time of the water. Approximately 80% of the daily intake of lead is from the ingestion of food, dirt and dust.