2007/22 – Numbulwar (Northern Territory) – E.coli, Hardness, Turbidity, Iron

Numbulwar (Northern Territory) – E.coli

2013/14: Numbulwar E.coli 4 detections, 98% e.coli compliance for year

2 August 2016: Numbulwar E.coli 3 detections, 1MPN/100mL in each sample

29 November 2017: Numbulwar E.coli 1 detection. 2 MPN/100mL

“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

Numbulwar – Northern Territory – Hardness

2008/09: Numbulwar Hardness 201mg/L

2009/10: Numbulwar Hardness 204mg/L

2021/22: Numbulwar Hardness 500mg/L (max), 400mg/L (av.)


“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.”

Numbulwar (Northern Territory) – Turbidity

2008/09: Numbulwar Turbidity 12NTU

2009/10: Numbulwar Turbidity 12NTU

2013/14: Numbulwar Turbidity 9.4NTU

2015/16: Numbulwar Turbidity 7.7NTU

2016/17: Numbulwar Turbidity 9,4NTU

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.

Numbulwar (Northern Territory) Iron

2007/08: Numbulwar Iron 0.47mg/L

2008/09: Numbulwar Iron 1.1mg/L

2009/10: Numbulwar Iron 1.31mg/L

2010/11: Numbulwar Iron 1.2mg/L

2013/14: Numbulwar Iron 1.1mg/L

2015/16: Numbulwar Iron 1.18mg/L

2016/17: Numbulwar Iron 0.97mg/L

2021/22: Numbulwar Iron 1mg/L (max), 0.5mg/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