2007/19: Alma (Victoria) – Trihalomethanes, Turbidity, Total Dissolved Solids, Hardness, pH

Alma (Victoria) Trihalomethanes

2007/8: Alma Victoria. 534μg/L

2008/9: Alma (Victoria) 0.49mg/L

7 & July 2008: Alma Reticulation (Maryborough System) 0.38mg/L (Commissioning of chloramination plant in November 2008 for water quality improvements. Informed DHS. One Section 22 submitted for all THM non-compliances expected to occur until 30 August 2009) CHWater Water Quality Report 2008/9.

6 October 2008: Alma Reticulation (Maryborough System) 0.37mg/L(Commissioning of chloramination plant in November 2008. Informed DHS. CHWater Water Quality Report 2008/9.

2014/15: Alma Trihalomethanes 280ug/L

Trihalomethanes Australian Guideline Level 0.25mg/L (250ug/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”. Source: https://water.epa.gov/drink/contaminants/index.cfm

Alma – Victoria – Turbidity (max levels)

2008/09: Alma (Victoria) – Turbidity 9.1 NTU

2016/17Alma Turbidity 11NTU

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.

Alma – Victoria – Total Dissolved Solids (Maximum levels)

2008/9: Alma (Victoria) – Total Dissolved Solids 1550 mg/L

2009/10: Alma (Victoria) – Total Dissolved Solids 850 mg/L

2010/11: Alma (Victoria) – Total Dissolved Solids 1000 mg/L

2015/16: Alma Total Dissolved Solids 700mg/L

2016/17: Alma Total Dissolved Solids 700mg/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

Alma – Victoria – Hardness (highest levels)

2008/09: Alma (Victoria) – Hardness 800mg/L

2009/10: Alma (Victoria) – Hardness 370mg/L

2013/14: Alma Hardness 210ug/L

2014/15: Alma Hardness 280ug/L

2015/16 Alma Hardness 390mg/L

2016/17: Alma Hardness 380ug/L

2018/19: Alma Hardness 220ugL


“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

Alma (Victoria) – pH (alkaline)

Average pH: 2017-18: 8.6 pH units

Average pH: 2018-19: 8.5 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.