2008/11 – Beaufort (Victoria) – E.coli, Trihalomethanes, Turbidity, Chlorine

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Beaufort (Victoria): E.coli

15/12/08 (3 days): Beaufort Customer Tap. 5 orgs/100mL Beaufort currently on “Boil Water Notice”. A number of resamples were collected, in the beginning these returned with E. coli, but then returned with zero E. coli. Informed DHS of initial and resample results.  (Central Highlands Water Annual Drinking Water Quality Report 2008-9)

22/12/08 (3 days): Beaufort Customer Tap. 1 org/100mL Notice sent to customers to remind of the need to boil water. Mains spot dosed with chlorine. No E. coli detected in resample.
Informed DHS of initial and resample results. (Central Highlands Water Annual Drinking Water Quality Report 2008-9)

12/1/09 (3 days): Beaufort Customer Tap. 1 org/100mL Beaufort currently on “Boil Water
Notice”. Resamples collected. Mains spot dosed with chlorine as part of mains cleaning program. Fax sent to businesses, hospitals and schools via emergency communications database. Second resample returned with no E. coli. Informed DHS. (Central Highlands Water Annual Drinking Water Quality Report 2008-9)

10/3/09 (6 days): Beaufort Customer Tap 1 org/100mL, 1 org/100mL, 2 orgs/100mL, 5 orgs/100mL Resamples collected from all four sites – two returned with E. coli. (3 and 5 orgs
/ 100mL). Mains flushed and decision made to chlorinate entire town. Following resample identified one site with E. coli (3 orgs / 100mL). Community advised of contamination, reminder to boil water and advising chlorine would be added to system following samples detected no
E. coli. DHS informed. (Central Highlands Water Annual Drinking Water Quality Report 2008-9)

15 August 2011 (3 days) Beaufort Clear Water Storage Tank, Beaufort E. coli – 4 org/100mL Beaufort Reticulation

“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

Beaufort (Victoria) – Trihalomethanes

2010/11: Beaufort (Victoria) – Trihalomethanes 0.24mg/L

Trihalomethanes Australian Guideline Level 250μg/L (0.25mg/L)

Why and how are THMs formed?
“When chlorine is added to water with organic material, such as algae, river weeds, and decaying leaves, THMs are formed. Residual chlorine molecules react with this harmless organic material to form a group of chlorinated chemical compounds, THMs. They are tasteless and odourless, but harmful and potentially toxic. The quantity of by-products formed is determined by several factors, such as the amount and type of organic material present in water, temperature, pH, chlorine dosage, contact time available for chlorine, and bromide concentration in the water. The organic matter in water mainly consists of a) humic substance, which is the organic portion of soil that remains after prolonged microbial decomposition formed by the decay of leaves, wood, and other vegetable matter; and b) fulvic acid, which is a water soluble substance of low molecular weight that is derived from humus”. US EPA

2011 Sep – Beaufort Victoria) – Turbidity

26 September 2011 (2 days) Beaufort Customer Tap Turbidity – 7.87 NTU Beaufort Reticulation

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

Beaufort (Victoria) – Chlorine

25th July 2012 (1 Day) Beaufort WTP Clear Water Storage Chlorine >5mg/L for 12 minutes Treated water flow from the Clear Water Storage was too low to match secondary chlorine pump capability Beaufort Customer Tap.

Based on health considerations, the guideline value for total chlorine in drinking water is 5 mg/L.

GENERAL DESCRIPTION
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