2003/17: Tennant Creek (Northern Territory) – E.coli, N. fowleri, Fluoride, Iodine, Hardness, Nitrate, Silica, Total Dissolved Solids

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Tennant Creek – E.coli

2003/4: Tennant Creek E coli  1org 100MPN 99.6% samples pass reporting level

2005/6: Tennant Creek: Total Exceedences E.coli 6. 97.6% of samples passing reporting level

2007/08: Tennant Creek E. coli  1 exceedance  99.0% of samples pass reporting level.

2008/9: Tennant Creek (Northern Territory) E.coli 3 exceedences. 97.2% of samples passing reporting level
2009/10: Tennant Creek E. coli  4 exceedences  96.6% of samples pass reporting level.

2010/11: Tennant Creek coli  2 exceedances. 98.1% of samples pass reporting level.

On 23 November 2011 E. coli was detected in samples from two locations in the Tennant Creek water supply collected on 21 November 2011. Operations personnel were notified immediately. To ensure public safety, DoH issued a water boil alert notice to the residents of Tennant Creek. Power and Water immediately isolated the tank that was suspected as being the source of the contamination. Both the storage and distribution system were manually chlorinated. The entire system was purged with chlorinated water. Samples were collected to assess the effectiveness of the remedial action. To ensure the supply of safe drinking water, Power and Water maintained manual daily chlorination while investigations continued. Following tank inspections and minor repairs to storage tank roofs and access hatches, daily chlorination was suspended on 27 November 2011. Samples collected after remedial actions were free of E. coli. Investigations suggested the contamination was attributed to frogs entering the tank via damaged hatches.

E.coli was again detected in samples collected on 12 December 2011. A water boil alert notice was not issued by DoH. The standard response was actioned. Storage and distribution systems were chlorinated and purged. Initial repairs to access hatches were inadequate requiring more appropriate repairs. Daily chlorination was maintained until the completion of repairs.

Further E. coli detections were reported on 9 January 2012, 24 January 2012, 6 February 2012, 20 February 2012, 12 March 2012 and 26 March 2012. In each case, temporary rectification was achieved with manual chlorination. Daily manual chlorination of the 5 ML tank has been maintained through to the end of this reporting period.

The total replacement of tank access hatches is planned during 2012-13. However, in the absence of the primary barrier, continuous disinfection, the Tennant Creek water supply remains unnecessarily vulnerable to microbiological contamination

Tennant Creek 26 November 2012: Samples with E.coli detections (2). Number of E.coli detected in sample (MPN/10ml) (2 and 2)
Tennant Creek 14 January 2013: Samples with E.coli detections (1). Number of E.coli detected in
sample (MPN/10ml) (1)

In Tennant Creek the recorded E. coli detections were prior to the installation of a continuous chlorination system. Since October 2014 and the investment in a continuous chlorination system, no E. coli has been detected in verification samples collected from this centre’s water supply. Power and Water Corporation Water Quality Report 2016

“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

Tennant Creek – N.fowleri

2015/16: All distribution systems and sources monitored during the 2012-16 were free of N. fowleri, with the exception of Gunn Point and Tennant Creek distribution systems.

“GUIDELINE No guideline value is set for Naegleria fowleri in drinking water, but an ‘action level’ is recommended for water supplies likely to be contaminated. If the organism is detected, advice should be sought from the relevant health authority.

Naegleria fowleri is a free-living, thermophilic amoeboflagellate which causes the waterborne disease primary amoebic meningoencephalitis (PAM). This rare but fatal condition has followed use of water for swimming, or domestic bathing. The organism occurs naturally in freshwater of suitable temperature, feeding on bacteria. Its occurrence is only indirectly related to human activity, inasmuch as such activity may modify temperatures or promote bacterial production. PAM has been reported from many countries, usually associated with thermally polluted environments, geothermal water or heated swimming pools. N. fowleri is almost exclusively aquatic, and water is the only known source of infection. Numerous nonvirulent Naegleria species are known in Australia.

PAM cases have been recorded from South Australia, Western Australia, Queensland and New South Wales; Naegleria fowleri has been detected in water in each of these states and in the Northern Territory. Australia is the only country where N. fowleri has been detected in public water supplies (Dorsch et al. 1983). Most of the available data on the density of N. fowleri in water relates to water supplies in South Australia (including the highest reported densities). In temperate Australia, significant seasonal cycles of density occur, from below one organism per litre to hundreds or thousands per litre in poorly disinfected water (Robinson and Christy 1984). N. fowleri detected at water temperatures below 18°C is likely to be present as cysts, which are not infectious, but which may seed a suitable environment.” Australian Drinking Water Guidelines 2011.

Tennant Creek (Northern Territory) – Fluoride

2005/6: Tennant Creek Fluoride 1.65mg/L

2006/07: Tennant Creek Fluoride 1.8mg/L

2007/08 Tennant Creek Fluoride 1.8mg/L

2008/9: Tennant Creek Fluoride 1.6mg/L

2009/10: Tennant Creek Fluoride 1.6mg/L

2010/11: Tennant Creek Fluoride 1.6mg/L

2011/12: Tennant Creek Fluoride 1.6mg/L

2012/13: Tennant Creek Fluoride 1.5mg/L

2013/14: Tennant Creek Fluoride 1.4mg/L

2014/15: Tennant Creek Fluoride 1.5mg/L

2015/16: Tennant Creek Fluoride 1.5mg/L

2016/17: Tennant Creek Fluoride 1.5mg/L

Australian Drinking Water Guideline 1.5mg/L

“Fluoride in the Tennant Creek water supply is managed to achieve an average below 1.5 mg/L, as recommended by the ADWG. This year’s average for Tennant Creek was 1.4 mg/L; however, as seen in Figure 10, the 95th percentile is above the guideline value. Timber Creek also has natural fluoride in the water supply. The average concentration level is below the guideline at 1.4 mg/L; however, Timber Creek has a 95th percentile level of 1.6 mg/L similar to Tennant
Creek.” Power and Water Annual Report 2006

Fluoride: ADWG Guideline: non-fluoridated water 1.5 milligrams per litre of drinking water
Fluoridated water 1.0 milligrams per litre of drinking water (rolling annual average). In Victoria, the Health (Fluoridation) Act 1973 states that the annual average for fluoride in drinking water shall not exceed a level of 1mg/L. It can be added to water supplies through the ‘Flurodose’ process. Fluoride is added to water either as fluosilicic acid (sometimes known as hydrofluosilicic acid) or sodium silicofluoride. It is sourced from superphosphate and is soluble.
Naturally occurring fluoride is almost insoluble and is known as calcium fluoride.
Use of Fluoride in water remains controversial. http://www.fluoridealert.org/

Tennant Creek – Northern Territory – Iodine

2003/4: Tennant Creek Iodine 0.2mg/L

2006/07: Tennant Creek Iodine 0.33mg/L

2007/8 Tennant Creek Iodine 0.35mg/L

2008/09: Tennant Creek Iodide 1.6mg/L

2009/10: Tennant Creek Iodine 0.36mg/L

2010/11: Tennant Creek Iodine 0.36mg/L

2011/12: Tennant Creek Iodine 0.35mg/L

Tennant Creek – Northern Territory – Hardness

2013/14: Tennant Creek Hardness 210mg/L

2015/16: Tennant Creek Hardness 200mg/L

2016/17: Tennant Creek Hardness 232mg/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.”

Pmara Jutunta (Northern Territory) – Nitrate

2009/10: Tennant Creek Nitrate 47mg/L

2010/11: Tennant Creek Nitrate 49mg/L

Nitrate: ADWG Guideline 50mg/L. Nitrate is the product of oxygenated nitrogen created from the breakdown of organic matter; lightning strikes; inorganic pesticides; or explosives. The Australian Drinking Water Guidelines recommend that nitrate levels between 50-100mg/L are a health consideration for infants less than three months, although levels up to 100mg/L can be safely consumed by adults. Mainly a problem in Northern Territory and some communities in Western Australia. “Cue, Meekatharra, Mount Magnet, New Norcia, Sandstone, Wiluna and Yalgoo have been granted an exemption from compliance with the nitrate guideline by the Department of Health. The water supplied is harmless to adults and children over the age of 3 months of age. Carers of infants younger than three months should seek advice from the Community Health Nurse regarding the use of alternative water sources for the preparation of bottle feeds. The Water Corporation provides bottled water free of charge for this purpose.”

Tennant Creek (Northern Territory) – Silica

2012/16: Tennant Creek Silica 88mg/L

2016/17: Tennant Creek Silica 84mg/L

To minimise an undesirable scale build up on surfaces, silica (SiO2) within drinking waters should not exceed 80 mg/L.
Silica present in water is usually referred to as amorphous silica (i.e. lacking any crystalline structure). When silica is dissolved within water it forms monosilicic acid:
SiO2 + 2H2O à Si(OH)4
When the concentrations of monosilicic acid increase, polymerisation of the silica occurs, forming polysilicic acids followed by formation of colloidal silica. Monosilicic acid and polysilicic acids are the forms of silica analysed when determining dissolved silica content.
The deposition of silica from solutions can occur via various mechanisms. The deposition of silica that can cause the most problems for the water industry is via silica’s ability to deposit on solid surfaces that have hydroxyl (OH) groups present. Surfaces that commonly have hydroxyl groups present are glass and metallic surfaces. For example, dissolved silica will react with the surfaces of glass and begin to form a white precipitate. The silica forms silicates on the surface, resulting in silica build-up. In cases where customer complaints occur due to scale build-up, water hardness and silica concentrations should be investigated to determine the cause.
Silica can be a problem in water treatment due to its ability to cause fouling of reverse osmosis (RO) membranes (Sheikholeslami and Tan, 1999, Ning 2002, Sahachaiyunta and Sheikholeslami 2002). This occurs when the dissolved silica of the concentrate becomes super-saturated, causing silicates to form in the presence of metals, and these deposit on the membrane surface. The silicate then dehydrates, forming hard layers on the membrane that reduce the effectiveness of the process… 2011 ADWG

Tennant Creek – Total Dissolved Solids

2016/17 – Tennant Creek Total Dissolved Solids 711mg/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