2007/17 – Ngukurr (Northern Territory) – E.coli, Selenium, Colour, Hardness, Total Dissolved Solids, Chloride, Turbidity, Iron

Ngukurr (Northern Territory) – E.coli

2009/10: Ngukurr E.coli 1detection during yearr. 99% E.coli performance during year

“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 2011

Ngukurr (Northern Territory)  Selenium

2007/08: Ngukurr Selenium 0.01mg/L

GUIDELINE

“Based on health considerations, the concentration of selenium in drinking water should not
exceed 0.01 mg/L.

Selenium and selenium salts are widespread in the environment. Selenium is released from natural and human-made sources, with the main source being the burning of coal. Selenium is also a by-product of the processing of sulfide ores, chiefly in the copper refining industry.

The major use of selenium is in the manufacture of electronic components. It is used in several other industries, and selenium compounds are used in some insecticides, in hair shampoos as an anti-dandruff agent, and as a nutritional feed additive for poultry and livestock.

Selenium concentrations in source waters are generally very low and depend on local geochemistry, pH and the presence of iron salts. Concentrations in drinking water supplies overseas are generally below 0.01 mg/L but groundwater concentrations as high as 6 mg/L have been reported in the United States.”

Australian Drinking Water Guidelines 2011

Ngukurr (Northern Territory) – Colour

2008/09: Ngukurr True Colour 21HU

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…”

Australian Drinking Water Guidelines 2011

Ngukurr – Northern Territory – Hardness

2007/08: Ngukurr Hardness 494mg/L

2008/09: Ngukurr Hardness 576mg/L

2009/10: Ngukurr Hardness 624mg/L

2010/11: Ngukurr Hardness 638mg/L

2013/14: Ngukurr Hardness 594mg/L

2015/16: Ngukurr Hardness 614mg/L

2016/17: Ngukurr Hardness 745mg/L

GUIDELINE

“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

Ngukurr – Northern Territory – Total Dissolved Solids

2007/08: Ngukurr Total Dissolved Solids 809mg/L

2010/11: Ngukurr Total Dissolved Solids 985mg/L

2013/14: Ngukurr Total Dissolved Solids 864mg/L

2015/16: Ngukurr Total Dissolved Solids 850mg/L

2016/17: Ngukurr Total Dissolved Solids 1051mg/L

GUIDELINE

“No specific health guideline value is provided for total dissolved solids (TDS), as there are no
health effects directly attributable to TDS. However for good palatability total dissolved solids
in drinking water should not exceed 600 mg/L.

Total dissolved solids (TDS) consist of inorganic salts and small amounts of organic matter that are dissolved in water. Clay particles, colloidal iron and manganese oxides and silica, fine enough to pass through a 0.45 micron filter membrane can also contribute to total dissolved solids.

Total dissolved solids comprise: sodium, potassium, calcium, magnesium, chloride, sulfate, bicarbonate, carbonate, silica, organic matter, fluoride, iron, manganese, nitrate, nitrite and phosphates…” Australian Drinking Water Guidelines 2011

Ngukurr (Northern Territory) – Chloride

2007/08: Ngukurr Chloride 286mg/L

2008/09: Ngukurr Chloride 343mg/L

2009/10: Ngukurr Chloride 399mg/L

2010/11: Ngukurr Chloride 398mg/L

2013/14: Ngukurr Chloride 333mg/L

2015/16: Ngukurr Chloride 330mg/L

2016/17: Ngukurr Chloride 491mg/L

“Chloride is present in natural waters from the dissolution of salt deposits, and contamination from effluent disposal. Sodium chloride is widely used in the production of industrial chemicals such as caustic soda, chlorine, and sodium chlorite and hypochlorite. Potassium chloride is used in the production of fertilisers.

The taste threshold of chloride in water is dependent on the associated cation but is in the range 200–300 mg/L. The chloride content of water can affect corrosion of pipes and fittings. It can also affect the solubility of metal ions.

In surface water, the concentration of chloride is usually less than 100 mg/L and frequently below 10 mg/L. Groundwater can have higher concentrations, particularly if there is salt water intrusion.

Based on aesthetic considerations, the chloride concentration in drinking water should not exceed 250 mg/L.

No health-based guideline value is proposed for chloride.” 2011 Australian Drinking Water Guidelines

Ngukurr (Northern Territory) – Turbidity

2008/09: Ngukurr Turbidity 14NTU

2009/10: Ngukurr Turbidity 5NTU

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.

Ngukurr (Northern Territory) Iron

2008/09: Ngukurr Iron 0.41mg/L

2010/11: Ngukurr Iron 0.41mg/L

2016/17: Ngukurr Iron 0.4mg/L

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