Australians are replacing soft drinks with bottled water and research suggests this habit is cutting our risk of obesity. Researchers at the Harvard School of Public Health found that a can of soft drink a day over four years can add more than 4kg to our weight. Fruit juice is little better, with almost as many kilojoules as standard soft drinks. Grabbing a chilled bottle of water, with zero kilojoules, is a dieter’s best option.
Chlorination can produce very small amounts of cancer-causing chemicals called trihalomethanes (THMs). However, the World Health Organisation says the risk of cancer from THMs is up to 1000 times less than the risk of death from bacteria in unchlorinated water. The Cancer Council of Western Australia reports that when 150 people drank water with chlorine levels ten times the NHMRC limit (during water mains disinfection) there were no side effects at all. And chlorine is not always the offender. “The thing that people are tasting and smelling is often natural, earthy molecules like geosmin,” says Michael Moore, director of the University of Queensland’s National Research Centre for Environmental Toxicology.
“Aluminium is added to tap water to clarify it and chlorine is added to make it safe,” says Tony Gentile of the Australasian Bottled Water Institute. “It is then delivered over long distances in pipes to homes.” Heavy metals such as copper and lead get into tap water from storage tanks and copper pipes, but are within safe limits, adds Dr Mike McLaughlin of the CSIRO. Bottled water is not entirely toxin-free either: metals tend to leach from rocks.
A choice poll found that 16% of people bought bottled water because they thought it tasted better than tap water. However, when the UK watchdog magazine Which? asked people to take part in a blind-tasting, half could not taste the difference and 18% actually preferred the flavour of tap water. Chlorine is used to disinfect tap water and it is most often blamed for any chemical aftertaste. “There is some minor smell from chlorine,” says water expert Dr Peter Gleick, president of the Pacific Institute, an environmental research centre in California. “But this actually means your tap water is safe. You want chlorine to kill off any pathogens.”