2004/17 – Larrimah (Northern Territory) – E.coli, Hardness, Total Dissolved Solids, Iodine

Larrimah (Northern Territory): E.coli
E.coli Total Exceedences 1. 97.4% Samples passing reporting level.
(Power & Water Corporation Water Quality Report 2006)

“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

Larrimah – Northern Territory – Hardness

2003/04: Larrimah Hardness 500mg/L

2004/05: Larrimah  Hardness 494mg/L

2005/06: Larrimah Hardness 497mg/L

2006/07: Larrimah Hardness 513mg/L

2007/08: Larrimah Hardness 513mg/L

2008/09: Larrimah  Hardness 522mg/L

2009/10: Larrimah Hardness 490mg/L

2010/11: Larrimah Hardness 487mg/L

2011/12: Larrimah Hardness 482mg/L

2012/13: Larrimah Hardness 483mg/L

2013/14: Larrimah Hardness 504mg/L

2014/15: Larrimah Hardness 465mg/L

2015/16: Larrimah Hardness 548mg/L

2016/17: Larrimah Hardness 523mg/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

Larrimah – Northern Territory – Total Dissolved Solids

2004/05: Larrimah Total Dissolved Solids 896 mg/L

2005/06: Larrimah Total Dissolved Solids 915 mg/L

2008/09: Larrimah Total Dissolved Solids 900 mg/L

2011/12: Larrimah Total Dissolved Solids 883mg/L

2012/13: Larrimah Total Dissolved Solids 949mg/L

2013/14: Larrimah Total Dissolved Solids 940mg/L

2014/15: Larrimah Total Dissolved Solids 944mg/L

2015/16: Larrimah Total Dissolved Solids 972mg/L

2016/17: Larrimah Total Dissolved Solids 935mg/L


“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

Larrimah – (Northern Territory) – Iodine

2006/07: Larrimah Iodine 0.117mg/L

2007/08: Larrimah Iodine 0.12mg/L

2008/09: Larrimah  Iodine 0.13mg/L

2009/10: Larrimah Iodine 0.12mg/L

2011/12: Larrimah Iodine 0.11mg/L

Iodide: Based on health considerations, the concentration of iodide in drinking water should
not exceed 0.5 mg/L.
Iodine: No guideline value has been set for molecular iodine.
The element iodine is present naturally in seawater, nitrate minerals and seaweed, mostly in the form of iodide salts. It may be present in water due to leaching from salt and mineral deposits. Iodide can be oxidised to molecular iodine with strong disinfectants such as chlorine.
Molecular iodine solutions are used as antiseptics and as sanitising agents in hospitals and laboratories.
Iodine is occasionally used for the emergency disinfection of water for field use but is not used for disinfecting larger drinking water supplies. Iodide is used in pharmaceutical and photographic materials. Iodine has a taste threshold in water of about 0.15 mg/L.
Iodide occurs in cows’ milk and seafood. Some countries add iodide to table salt to compensate for iodide-deficient diets.