Halifax (Queensland) – Aluminium

Sampling for aluminium in raw water sources shows small quantities in all bores, except for two abnormal  historical results that occurred in a Macknade Combined Bore sample and a Halifax Combined Bore sample. On 21st June 2000 a sample was taken for aluminium from both the Macknade Combined Bore and the Halifax Combined Bore and the reading for aluminium was 0.8 mg/L and 0.17 mg/L respectively. These results were a large variation against the other samples taken over the period. These bores have been rehabilitated within the
past 5 years and the latest readings show low levels. Aluminium levels in the treated and reticulated water remain constant and do not show any trends, exceedances or spikes.

According to the ADWG, no health guideline has been adopted for Aluminium, but that the issue is still open to review. Aluminium can come from natural geological sources or from the use of aluminium salts as coagulants in water treatment plants. According to the ADWG “A well-operated water filtration plant (even using aluminium as a flocculant) can achieve aluminium concentrations in the finished water of less than 0.1 mg/L.

The most common form of aluminium in water treatment plants is Aluminium Sulfate (Alum). Alum can be supplied as a bulk liquid or in granular form. It is used at water treatment plants as a coagulant to remove turbidity, microorganisms, organic matter and inorganic chemicals. If water is particularly dirty an Alum dose of as high as 500mg/L could occur. There is also concern that other metals may also exist in refined alum.

While the ADWG mentions that there is considerable evidence that Aluminium is neurotoxic and can pass the gut barrier to accumulate in the blood, leading to a condition called encephalopathy (dialysis dementia) and that Aluminium has been associated with Parkinsonism dementia and amyotrophic lateral sclerosis, the NHMRC, whilst also acknowledging studies which have linked Aluminium with Alzheimer disease, has not granted Aluminium a NOEL (No Observable Effect Level) due to insufficient and contradictory data. Without a NOEL, a health guideline cannot be established. The NHMRC has also stated that if new information comes to hand, a health guideline may be established in the future.

In communication with Aluminium expert Dr Chris Exley (Professor in Bioinorganic Chemistry
The Birchall Centre, Lennard-Jones Laboratories, Keele University, Staffordshire UK) in March 2013 regarding high levels of Aluminium detected in the South Western Victorian town of Hamilton
“It is my opinion that any value above 0.5 mg/L is totally unacceptable and a potential health risk. Where such values are maintained over days, weeks or even months, as indeed is indicated by the data you sent to me, these represent a significant health risk to all consumers. While consumers may not experience any short term health effects the result of longer term exposure to elevated levels of aluminium in potable waters may be a significant increase in the body burden of aluminium in these individuals. This artificially increased body burden will not return to ‘normal’ levels when the Al content of the potable water returns to normal but will act as a new platform level from which the Al body burden will continue to increase with age.

Halifax (Queensland) – Chloride

Some high levels of chloride in the raw water have been recorded at Halifax that exceeds the ADWG. Halifax  Bore 3 had the highest record of 590 mg/L in 2015. However, the maximum over the past 5 years was 47 indicating that the decommissioning of the Halifax system has improved raw water quality. Chloride levels for  treated and reticulation water are well below the guideline.

“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.

Halifax (Queensland) – Sodium

Historical sodium levels in raw water were slightly higher in the Halifax bores than the Macknade Bores. There were some peaks identified in Halifax Bore 3 (maximum 321 mg/L) and Halifax Bore 5 (maximum 150 mg/L). however, the maximum value was 40 mg/L in the past 5 years and is due to using Macknade bores. Sodium levels in treated and reticulated water are below the guideline and show no trends or abnormal results.

“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

Halifax (Queensland) – Total Dissolved Solids.

Raw water data for the level of total dissolved solids is scattered. In general, the Halifax bores have a higher reading of total dissolved solids in the raw water. The maximum level of 1190 mg/L was recorded at Halifax Bore 3 in 2015. A maximum level of 189 mg/L was recorded since 2015 indicating that the removal of the Halifax system has been beneficial. Similar results were found in the treated and reticulated water.

GUIDELINE

“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

Halifax (Queensland) – Turbidity

For the past 5 years, turbidity levels in raw water are quite scattered, but the majority of the sampling shows  that the turbidity in raw water falls below 5 NTU. The maximum result was 13 NTU. The maximum treated water turbidity was 4 NTU, and 2 NTU in the reticulation system. An operational procedure is planned to select raw water sources to improve overall water quality.

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