The concentration and prevalence of asbestos fibres in Christchurch, New Zealand’s drinking water supply

Asbestos cement was a common construction material for water pipes during the twentieth century, as a replacement for metal piping that was vulnerable to corrosion. We report on the presence of asbestos fibres in drinking water supply in Christchurch, New Zealand from ageing asbestos cement reticulated water supply. By sampling the mains water supply via hydrants, 19 of our 20 samples showed long asbestos fibres (.10 μm), with an average concentration 0.9 million fibres per litre (MFL). Short asbestos fibres (.0.5 μm) had an average concentration of 6.2 MFL. Sampling was targeted to pipes from 1930 to the 1960s and there was abundant evidence of fibres being released from pipes of this age. Municipalities cannot continue to rely on ageing asbestos-cement piping, as it appears to be releasing asbestos fibres into drinking water with uncertain health implications, and should prioritise replacing pipes greater than 50 years in age, especially where high water pressures or land disturbance occur, to reduce the risk of water-carried asbestos being released into urban environments, and mitigate any risk of asbestos from ingested contaminated water sources.