Water authorities, under the Water Supply Code of Australia, are required to disinfect new water mains before putting them into service to protect public health. Sydney Water’s traditional practice is to disinfect new mains using super chlorinated water for 24 hours. The super chlorinated water is then flushed out into the environment. The super chlorinated water has the potential to damage the environment so it must be dechlorinated prior to discharge. Mains disinfection using chlorine has a small but real risk of supplying highly chlorinated water to customers.
During the recent prolonged drought, water restrictions were introduced by the NSW Government. Sydney Water led a successful customer behavioural change program on water efficiency, however there was public concern in relation to water wastage in the mains chlorination process. Equally legitimate concerns were raised by the property development industry when delays were experienced connecting water mains to new developments.
Ozone is a very strong oxidant with the added advantage of breaking down rapidly into harmless Oxygen. These two properties make ozone attractive for the water mains disinfection process - Ozone provides a high level of confidence in regards to bacterial inactivation while being able to break down as the job is being completed. This reduces the risk in relation to chemicals coming into contact with operators (in terms of health and safety) and eliminates the risk of causing environmental harm.