Natimuk (Victoria)

Highest Level Only

2011/12: Natimuk Trihalomethanes 0.28mg/L (max)

2010/11: Natimuk Trihalomethanes 0.27mg/L (max)

2022/23: Natimuk (Trihalomethanes) 0.29mg/L (max), 0.146mg/L (av.)

There was an exceedance of trihalomethanes above the 0.25 mg/L limit of the Regulations
in the locality of Natimuk on 5 January 2023 of 0.29 mg/L. This was rapidly resolved by
decreasing the chlorine dosing rate at Natimuk PS, flushing of the relevant section of the
reticulation, with resamples returning results below the regulated limit.

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”. Source: https://water.epa.gov/drink/contaminants/index.cfm