2016/23 – Parachilna (South Australia) – Chloride, Chlorate, Sodium, Total Dissolved Solids, Hardness

Parachilna (South Australia) – Chloride

August 24 2016 Parachilna (South Australia)  Chloride 301mg/L

November 16 2016 Parachilna (South Australia)  Chloride 303mg/L

March 8 2017 Parachilna (South Australia)  Chloride 311mg/L

May 31 2017 Parachilna (South Australia)  Chloride 297mg/L

2018/19: Parachilna (South Australia) Chloride 300mg/L (max), 288.5mg/L (av.)

2019/20: Parachilna Chloride 304mg/L (max). 289.5mg/L av.

2022/23: Parachilna Chloride 296mg/L (max). 283.23mg/L av.

“Chloride is present in natural waters from the dissolution of salt deposits, and contamination from effluent disposal. Sodium chloride is widely used in the production of industrial chemicals such as caustic soda, chlorine, and sodium chlorite and hypochlorite. Potassium chloride is used in the production of fertilisers.

The taste threshold of chloride in water is dependent on the associated cation but is in the range 200–300 mg/L. The chloride content of water can affect corrosion of pipes and fittings. It can also affect the solubility of metal ions.

In surface water, the concentration of chloride is usually less than 100 mg/L and frequently below 10 mg/L. Groundwater can have higher concentrations, particularly if there is salt water intrusion.

Based on aesthetic considerations, the chloride concentration in drinking water should not exceed 250 mg/L.

No health-based guideline value is proposed for chloride.” 2011 Australian Drinking Water Guidelines

2016: Parachilna (South Australia) – Chlorate

7/9/16: Parachilna (South Australia) – Chlorate 0.54mg/L

Incident Description: The first non-compliance was a detection of chlorate from a routine sample taken from the Jericho Water Treatment Plant and the Alpha Water Treatment Plant. As Chlorate is a parameter with no reporting limit, any detection is reported immediately to the Department and results are monitored monthly. Corrective and Preventative Actions: Council are conducting further investigations into how to minimise chlorate occurrences, by looking to delivery methods and storage of chemicals.

Chlorite: ADWG Health 0.3mg/L.

Chlorite and chlorate are disinfection by-products of chlorine dioxide disinfection process.

“… industry are having serious problems meeting chlorite/chlorate limits that were proposed in the new Australian Drinking Water Guidelines, especially for disinfection in long distance pipelines that are dosed with sodium hyptochlorite” pers comm 18/5/11.

“Chlorite occurs in drinking water when chlorine dioxide is used for purification purposes. The
International Agency for Research on Cancer (IARC) has concluded that chlorite is not classifiable as carcinogenic to humans and is listed in the Group 3 category. Changes in red blood vessels due to oxidative stress are a major concern with excessive levels of Chlorite in drinking water. According to the US EPA, potential health problems for people drinking Chorite above safe drinking water guideline include: Anemia in infants and young children and nervous system effects.” https://water.epa.gov/drink/contaminants/index.cfm

“Chlorine dioxide (chlorite) is rarely used as a disinfectant in Australian reticulated supplies.
When used, the chlorite residual is generally maintained between 0.2mg/L and 0.4mg/L. It is
particularly effective inthe control of manganese-reducing bacteria. Few data are available on
chlorate levels in Australian water supplies….Chlorine dioxide, chlorite, and chlorate are all
absorbed rapidly by the gastrointestinal tract into blood plasma and distributed to the major
organs. All compounds appear to be rapidly metabolised. Chlorine dioxide has been shown to
impair neurobehavioural and neurological development in rats exposed before birth. Experimental studies with rats and monkeys exposed to chlorine dioxide in drinking water have shown some evidence of thyroid toxicity; however, because of the studies’ limitations, it is difficult to draw firm conclusions (WHO 2005) The primary concern with chlorite and chlorate is oxidative stress resulting in changes in red blood cells. This end point is seen in laboratory animals and, by analogy with chlorate, in humans exposed to high doses in poisoning incidents (WHO 2005).” Australian Drinking Water Guidelines – National Health and Medical Research Centre

“…Subchronic studies in animals (cats, mice, rats and monkeys) indicate that chlorite and chlorate cause haematological changes (osmotic fragility, oxidative stress, increase in mean corpuscular volume), stomach lesions and increased spleen and adrenal weights… Neurobehavioural effects (lowered auditory startle amplitude, decreased brain weight and decreased exploratory activity) are the most sensitive endpoints following oral exposure to chlorite…” https://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/chlorite-chlorate/indexeng.
php#sec10_1Guidelines for Canadian Drinking Water Quality.

Parachilna (South Australia) – Sodium

24/8/16 Parachilna  Sodium 192mg/L

16/11/16 Parachilna Sodium 178mg/L

8/3/17 Parachilna Sodium 190mg/L

31/5/17 Parachilna Sodium 188mg/L

2018/19: Parachilna (South Australia) Sodium 204mg/L (max), 185.25mg/L (av.)

2022/23: Parachilna (South Australia) Sodium 187mg/L (max), 178.75mg/L (av.)

“Based on aesthetic considerations (taste), the concentration of sodium in drinking water
should not exceed 180 mg/L….The sodium ion is widespread in water due to the high solubility of sodium salts and the abundance of mineral deposits. Near coastal areas, windborne sea spray can make an important contribution either by fallout onto land surfaces where it can drain to drinking water sources, or from washout by rain. Apart from saline intrusion and natural contamination, water treatment chemicals, domestic water softeners and
sewage effluent can contribute to the sodium content of drinking water.” ADWG 2011

Parachilna (South Australia) – Total Dissolved Solids

2018/19: Parachilna (South Australia) Total Dissolved Solids 840mg/L (max), 835mg/L (av)

2019/20: Parachilna Total Dissolved Solids (by EC) 846mg/L (max), 838.5mg/L av.

2022/23: Parachilna Total Dissolved Solids (by EC) 834mg/L (max), 830mg/L av.


“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

Parachilna (South Australia) – Hardness

2018/19: Parachilna (South Australia) Hardness as CaCO3 313mg/L (max), 310.25mg/L (mean)

2019/20: Parachilna Total Hardness as CaCO3 305mg/L (max), 301.75mg/L av.


“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