2015/20 – Charters Towers (Queensland) – E.coli, Cadmium, Lead, Chlorine, Colour, Hardness, Turbidity, Iron

2015/16 – Charters Towers Reservoir – E.coli

E.coli Detection–Charters Towers Reservoir: E.coli was detected in a sample (and its duplicate) collected from the Charters Towers Steel Reservoir and immediately reported – Incident No. DWI-7-479-00009 (20/02/2016) refers. Corrective actions (flushing, retest) were as directed by DEWS; all subsequent testing showed no further detection. Reason was found to be that the
sample was taken from an incorrect sampling point without following correct flushing procedures. Staff have been retrained in correct sampling techniques.
2015/16: Charters Towers Drinking Water Quality Management Plan

“Coliforms are Gram-negative, non-spore-forming, rod-shaped bacteria that are capable of aerobic and facultative anaerobic growth in the presence of bile salts or other surface active agents with similar growth-inhibiting properties. They are found in large numbers in the faeces of humans and other warm-blooded animals, but many species also occur in the environment.

Thermotolerant coliforms are a sub-group of coliforms that are able to grow at 44.5 ± 0.2°C. E. coli is the most common thermotolerant coliform present in faeces and is regarded as the most specific indicator of recent faecal contamination because generally it is not capable of growth in the environment. In contrast, some other thermotolerant coliforms (including strains of Klebsiella, Citrobacter and Enterobacter) are able to grow in the environment and their presence is not necessarily related to faecal contamination. While tests for thermotolerant coliforms can be simpler than for E. coli, E. coli is considered a superior indicator for detecting faecal contamination…” ADWG

2015/16 – Charters Towers Reservoir – Cadmium

Cadmium Detection–Charters Towers Reservoir: On May the 4th 2016 during a routine analysis, it was found by Townsville Laboratories that a sample taken at the Charters Towers Steel reservoir exceeded the ADWG health value of .002mg/L for Cadmium. The reported level was 0.0042 mg/L, the subsequent investigation found that an old galvanised test point was used
giving a false indication. Corrective actions (retest) were as directed by DEWS; all subsequent testing found no elevated Cadmium results (as reported in the investigation report). Gal sample point isolated.
2015/16: Charters Towers Drinking Water Quality Management Plan

ADWG Cadmium Guideline. 0.002mg/L

The primary route of exposure of cadmium is via contaminated water or food. Fertiliser can be a source of excessive cadmium as can rainwater tanks. It has been linked to cancer, lung disorders, kidney disease and autoimmune disease.

2016/17 – Charters Towers Service Area – Lead

2016/17: Charters Towers – Lead 0.012mg/L? (highest level)

2016/17: Charters Towers Drinking Water Quality Management Plan

Lead Australian Drinking Water Guideline 0.01mg/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.

Lead is the most common of the heavy metals and is mined widely throughout the world. It is used in the production of lead acid batteries, solder, alloys, cable sheathing, paint pigments, rust inhibitors, ammunition, glazes and plastic stabilisers. The organo-lead compounds tetramethyl and tetraethyl lead are used extensively as anti-knock and lubricating compounds in gasoline…ADWG 2011

Charters Towers (Qld) Chlorine

2017/18: Charters Towers (Qld) Chlorine 5.71mg/L (max), 1.39mg/L (mean)

Chlorine dissociates in water to form free chlorine, which consists of aqueous molecular chlorine, hypochlorous acid and hypochlorite ion. Chlorine and hypochlorites are toxic to microorganisms and are used extensively as disinfectants for drinking water supplies. Chlorine is also used to disinfect sewage and wastewater, swimming pool water, in-plant supplies, and industrial cooling water.

Chlorine has an odour threshold in drinking water of about 0.6 mg/L, but some people are particularly sensitive and can detect amounts as low as 0.2 mg/L. Water authorities may need to exceed the odour threshold value of 0.6 mg/L in order to maintain an effective disinfectant residual.

In the food industry, chlorine and hypochlorites are used for general sanitation and for odour control. Large amounts of chlorine are used in the production of industrial and domestic disinfectants and bleaches, and it is used in the synthesis of a large range of chemical compounds.

Free chlorine reacts with ammonia and certain nitrogen compounds to form combined chlorine. With ammonia, chlorine forms chloramines (monochloramine, dichloramine and nitrogen trichloride or trichloramine) (APHA 2012). Chloramines are used for disinfection but are weaker oxidising agents than free chlorine.

Free chlorine and combined chlorine may be present simultaneously (APHA 2012). The term totalchlorine refers to the sum of free chlorine and combined chlorine present in a sample.

Chlorine (Free) ADWG Guideline: 5mg/L (Chlorine in chloraminated supplies 4.1mg/L). Chlorine dissociates in water to form free chlorine, which consists of aqueous molecular chlorine, hypochlorous acid and hypochlorite ion.

Chlorine (Total) ADWG Guideline 5mg/L (chloraminated supplies 4.1mg/L): The term total chlorine refers to the sum of free chlorine and combined chlorine present in a sample

2016/17 – Charters Towers Service Area – Colour

2016/17: Charters Towers – Colour 1431 Pt-Co Units (highest level), av 66.91

Based on aesthetic considerations, true colour in drinking water should not exceed 15 HU.

“… Colour is generally related to organic content, and while colour derived from natural sources such as humic and fulvic acids is not a health consideration, chlorination of such water can produce a variety of chlorinated organic compounds as by-products (see Section 6.3.2 on disinfection by-products). If the colour is high at the time of disinfection, then the water should be checked for disinfection by-products. It should be noted, however, that low colour at the time of disinfection does not necessarily mean that the concentration of disinfection by-products will be low…

2016/17 – Charters Towers Service Area – Hardness

2015/16: Charters Towers Service Area – Hardness 360.7mg/kg CO3/L, av. 258.85mg/kg CO3/L

2016/17: Charters Towers Service Area – Hardness 571.1mg/kg CO3/L, av. 279.46mg/kg CO3/L


“To minimise undesirable build‑up of scale in hot water systems, total hardness (as calcium
carbonate) in drinking water should not exceed 200 mg/L.

Hard water requires more soap than soft water to obtain a lather. It can also cause scale to form on hot water pipes and fittings. Hardness is caused primarily by the presence of calcium and magnesium ions, although other cations such as strontium, iron, manganese and barium can also contribute.”

Australian Drinking Water Guidelines 2011

2016/17 – Charters Towers Service Area – Turbidity

2016/17: Charters Towers Service Area – Turbidity 1030NTU (max), 59.86av.

Chlorine-resistant pathogen reduction: Where filtration alone is used as the water treatment
process to address identified risks from Cryptosporidium and Giardia, it is essential
that filtration is optimised and consequently the target for the turbidity of water leaving
individual filters should be less than 0.2 NTU, and should not exceed 0.5 NTU at any time
Disinfection: A turbidity of less than 1 NTU is desirable at the time of disinfection with
chlorine unless a higher value can be validated in a specific context.

Aesthetic: Based on aesthetic considerations, the turbidity should not exceed 5 NTU at the
consumer’s tap

Charters Towers (Qld) – Iron

2019/20: Charters Towers (Qld) – Iron 0.43mg/L (max), 0.035mg/L (av.)

Based on aesthetic considerations (precipitation of iron from solution and taste),
the concentration of iron in drinking water should not exceed 0.3 mg/L.
No health-based guideline value has been set for iron.

Iron has a taste threshold of about 0.3 mg/L in water, and becomes objectionable above 3 mg/L. High iron concentrations give water an undesirable rust-brown appearance and can cause staining of laundry and plumbing fittings, fouling of ion-exchange softeners, and blockages in irrigation systems. Growths of iron bacteria, which concentrate iron, may cause taste and odour problems and lead to pipe restrictions, blockages and corrosion. ADWG 2011