Abstract
Asbestos cement piping was used worldwide for its relative strength, thermal and chemical resistance, and technical superiority to previous piping materials. However, in the 1970s, it became evident that coincident with pipe deterioration (corrosion), asbestos fibres could be released into the potable water supply. Global restrictions were enforced on the use and manufacture of asbestos in construction materials in the 1980s and health risks associated with aerosolised asbestos fibres lead to the decline of its use in water mains. Yet, despite the widespread cessation of use of asbestos in construction materials in the 1980s, extensive lengths of asbestos cement piping still remain in use worldwide. These pipes, which peaked in installation between the 1940s–1960s, have now reached their end of life. This thesis reports on the presence of asbestos fibres in drinking water supply in Christchurch, New Zealand from aging asbestos cement water mains.
The potable water supply network in Christchurch is comprised of 1814 km of pipe, 789 km of which is active asbestos cement. The data presented in this work establishes the first TEM analysed exposure data for asbestos in drinking water in New Zealand and builds a reliable methodological foundation for future research. The results from the TEM analysis indicated that an aged asbestos cement piped network (>50 years old) was releasing short (i.e., >0.5 µm) and long (i.e., > 10 µm) asbestos fibres into the potable water supply of Christchurch. Cast-iron pipes installed before 1940 are assumed to contain lead jointing in Christchurch and have been in use in some localities for over 100 years. When these pipe joints corrode it presents a risk of exposing the potable water supply to lead contamination. Drinking water samples exposed to cast-iron pipes were analysed for the presence of lead. End-use consumer locations were sampled for both lead and copper by 5-minute flush and first draw sampling protocols to investigate the dissolution of consumer plumbed materials (i.e., tapware and copper pipes). There were no significant detections of lead or copper concentrations in the drinking water samples exposed to lead joiners or consumer plumbed materials.