Lock (South Australia) – Trihalomethanes
Breaches to Australian Drinking Water Guidelines Levels Only
Nov 2000? Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 342 ug/L
16/01/2001 Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 599 ug/L
26/03/2001 Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 330 ug/L
22/01/2002 Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 655 ug/L
20/03/2002 Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 366 ug/L
28/05/2002 Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 252 ug/L
18/12/2007 Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 315 ug/L
18/12/2007 Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 297 ug/L
15/01/2008 Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 288 ug/L
12/02/2008 Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 287 ug/L
17/06/2008 Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 270 ug/L
1/05/13 Lock Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 259 ug/L
28/08/13 Lock Lock 3 Railway Tce (SAW Depot) Trihalomethanes – Total 277 ug/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”. Source: https://water.epa.gov/drink/contaminants/ind
Lock (South Australia) – pH (alkaline)
2018/19: Lock (South Australia) 8.683 pH units (av)
2019/20: Lock (South Australia) 8.76 pH units (av)
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.
Lock (South Australia) – Turbidity
1/10/19: Lock (South Australia) Turbidity 7.8 NTU (max). 2019/20 av: 0.98NTU
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
Lock (South Australia) – Chloral Hydrate
1/6/10 Lock Chloral Hydrate 25.8ug/L
26/6/12 Lock Chloral Hydrate 32.5ug/L
Chloral hydrate is a disinfection by-product, arising from chlorination of water containing naturally occurring organic material (NOM). Chloral hydrate is a sedative and hypnotic drug. Long-term use of chloral hydrate is associated with a rapid development of tolerance to its effects and possible addiction as well as adverse effects including rashes, gastric
discomfort and severe renal, cardiac and hepatic failure.
2004 Australian Drinking Water Guideline: Trichloroacetaldehyde (chloral hydrate): 0.02mg/L
2011 Australian Drinking Water Guideline: Trichloroacetaldehyde (chloral hydrate): 0.1mg/L