Asbestos fibres in drinking water
The Asbestos and Silica Safety and Eradication Agency (ASSEA) partnered with a research team from Deakin University to investigate the levels of asbestos fibres in drinking water that has passed through asbestos-cement (AC) pipes. Australia has approximately 40,000 km of AC drinking water pipes, this being nearly 20% of the total length of the nation’s drinking water pipes.
In a 2021 report Asbestos in drinking water: Background document for development of WHO Guidelines for drinking-water quality, the World Health Organization (WHO) noted that based on a weight of evidence approach, there is no risk to human health from the consumption of asbestos fibres in water. Nonetheless, due to the uncertainties and limitations of epidemiological data, the WHO recommended that ‘it is appropriate to try to minimise the concentrations of asbestos fibres in drinking water as far as practical’, and that it would be ‘useful to conduct investigative monitoring to obtain further information on the contribution of older AC pipes to fibre numbers, types, size and shape in drinking-water’. The ASSEA sponsored project gave effect to the recommendations of the WHO.
The aim of the project was to evaluate the levels of asbestos fibres in drinking water supplied through AC pipes, while concurrently gathering data and information on factors that may influence the levels of asbestos fibres in water. Those factors include daily variation in the demand for water, water pressure, distance from a water treatment plant, and aspects of water chemistry (e.g. pH, levels of representative inorganic ions, total solids). The project was also designed to develop a robust and standardised water sampling procedure that can be used to determine representative levels of asbestos fibres in drinking water distribution systems in any location. A ‘Working Group’, consisting of representatives from both government and non-government bodies, acted as a consultative body, assisting in planning and providing advice with respect to the work.
In both the summer (February) and winter (June) of 2024, the university research team took samples of drinking water that had passed through AC pipes in the regional Victorian town of Shepparton. These samples were analysed for asbestos fibres by a laboratory accredited by the National Association of Testing Authorities (NATA) for the testing of the presence of AC fibres in water. Chemical analysis was also conducted by the research team for other attributes of the water, such as pH, temperature, dissolved metals, and dissolved solids.
Asbestos fibres were not detected in any of the water samples. The water chemistry of the samples was in-line with that previously measured by the water authority over the last decade and did not show substantial differences between summer and winter. Water pressure at the locations was stable during the day, indicating that any possible effect of dynamic pressure on the release of asbestos fibres was minimal. The calculated Aggressive Index (AI) and Langelier Saturation Index (LSI) values indicate the water was aggressive and corrosive, suggesting it is unlikely that calcium carbonate has accumulated on the inside walls of the pipes. Given no asbestos fibres were found in the water, it seems likely the AI and LSI qualities of the water have had little or no effect on the asbestos-cement matrix of the pipes themselves. The methodology that the research partner developed should be applicable for the sampling of water in other locations in Australia.
Any decision on future work will be taken by ASSEA after consultation and advice from the Working Group.
