2008/13 + 2017/21 – Skipton (Victoria) – E.coli, Trihalomethanes, Hardness, Iron, pH

Skipton (Victoria) – E.coli

26 September 2011 (3 days) Skipton Customer Tap (Ballarat System) E. coli – 1 org/100mL Skipton Reticulation (Ballarat System)

“E.coli

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

Skipton (Victoria) – Trihalomethanes

18th March 2013 (17 Days) Time period from date of detection to the time chloramine was re-instated Skipton Customer Tap (Ballarat System) Trihalomethanes (THMs) – 0.27 mg/L Skipton Reticulation (Ballarat System)

Trihalomethanes Australian Guideline Level 250μg/L

“The raw water at Katamatite is sourced from the Murray Valley Channel irrigation system which is managed by Goulburn Murray Water. Normal operation of this channel system involves the

shutdown over the winter period with no water available, GVW is required to fill the storages prior to the shutdown of the irrigation system and is reliant upon storage until irrigation water becomes available. At the time of the exceedance the raw water levels in the onsite storages were low due to this shutdown period and sourcing water over winter from the storage. The low raw water storage levels resulted in a higher concentration of dissolved organic matter within the storage, which increased the chlorine demand. Shortly after the exceedance GVW were able to access water in the irrigations system, improving the water quality and reducing the levels of organic matter present. All subsequent resamples were below the health limit.”

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

Skipton – Victoria – Hardness

2008/09: Skipton (Victoria) – Hardness 260mg/L (Highest Detection Only)

2009/10: Skipton (Victoria) – Hardness 220mg/L (Highest Detection Only)

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

Skipton (Victoria) – Iron

2010/11: Skipton (Victoria) Iron 0.49mg/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

Skipton (Victoria) – pH (alkaline)

Skipton Average pH: 2017-18: 8.6 pH units

Skipton Average pH: 2018-19: 8.6 pH units

Skipton Average pH: 2020-21: 8.6 pH units

Based on the need to reduce corrosion and encrustation in pipes and fittings, the pH of
drinking water should be between 6.5 and 8.5.

New concrete tanks and cement-mortar lined pipes can significantly increase pH and
a value up to 9.2 may be tolerated, provided monitoring indicates no deterioration in
microbiological quality.

pH is a measure of the hydrogen ion concentration of water. It is measured on a logarithmic scale from 0 to 14. A pH of 7 is neutral, greater than 7 is alkaline, and less than 7 is acidic.

One of the major objectives in controlling pH is to minimise corrosion and encrustation in pipes and fittings. Corrosion can be reduced by the formation of a protective layer of calcium carbonate on the inside of the pipe or fitting, and the formation of this layer is affected by pH, temperature, the availability of calcium (hardness) and carbon dioxide. If the water is too alkaline (above pH 8.5), the rapid deposition and build-up of calcium carbonate that can result may eventually block the pipe.