Brookton (Western Australia) – Trihalomethanes
Western Australia THM’s Highest readings Ballingup 0.361mg/L (2003/4)
In Western Australia 2002-11: 27 THM readings above 0.250mg/L.
Australian Drinking Water Guideline Level (Trihalomethanes) 0.250mg/L (250ug/L) (US Guideline 0.08mg/L)
Classical trihalomethanes consist of chloroform (CHCl3), dichlorobromoform (CHCl2Br),
dibromochloroform (CHBr2Cl) and bromoform (CHBr3).
“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 odorless, but harmful and potentially toxic. The quantity of byproducts 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”.