Our Precious Drinking Water
Most of Melbourne's water comes from uninhabited mountain ash forests high up in the Yarra Ranges to the east. For more than 100 years, these water catchments have been closed to the public. There are now more than 157,000 hectares reserved for the primary purpose of harvesting water. Melbourne is one of only about five cities in the world that has such protected catchments.
Melbourne's water supply system is based on the principle that it is better to start with the highest quality source water than having to treat it to reach required standards.
Protecting the catchments
Safeguarding Melbourne's water supply catchments is a priority for Melbourne Water.
Bushfires, erosion and unauthorised public entry are the main risks that we manage to ensure our pristine source water is protected.
Bushfires leave soot and ash, which can be washed from the catchments into the reservoirs. Fires can also destroy the mountain ash trees that cover about half the catchment areas. Firefighters are on call over Summer to try to ensure that any fires that start do not take hold.
Melbourne Water invests about $1 million a year on fire prevention and suppression to protect the security and quality of our water supplies.
Melbourne Water also pays particular attention to roads in the catchments to ensure appropriate drainage is constructed and maintained to minimise erosion and sediment flowing into the water.
We also restrict public access to the catchments to minimise the risk of humanborne disease and chemical contaminants entering our water supply system. The system of protected catchments provides a significant barrier against contamination of the water supply by Cryptosporidium, Giardia and other parasites.
In recent years, we have increased security for the catchments and our water supply assets by upgrading signage and security systems. Our security team patrols the water supply catchments regularly.
How Melbourne's water supply system works
Melbourne's water supply system includes the catchments, storage reservoirs, large transfer mains, local service reservoirs and water treatment facilities.
Melbourne Water manages nine major reservoirs that provide Melbourne with a capacity of 1,773,000 million litres of water.
We also operate approximately 1300 kilometres of distribution mains and aqueducts, 64 service reservoirs, 18 water pumping stations, five water filtration plants and 49 water treatment (disinfection) plants.
What's in your water besides H2O?
Very little. Since about 90% of Melbourne's water comes from protected catchments, most of our water requires minimal treatment before being supplied to our retail customers.
All water supplied to these water companies is disinfected to ensure the water is free from microorganisms that can cause disease.
Minimal treatment
The treatment process involves disinfection, fluoridation and pH correction. The addition of chemicals is continuously monitored and controlled to ensure the correct amounts are added to our water.
Chlorination is the preferred method of disinfection to ensure safe water is provided throughout the extensive distribution system in Melbourne.
Small amounts of chlorine are added to destroy any waterborne disease-causing microorganisms. The amount of chlorine added is equivalent to less than half a teacup in an average-size backyard swimming pool.
Melbourne Water is required under the Fluoridation Act 1973 to fluoridate the drinking water supply to help prevent tooth decay. Fluoridation of drinking water is supported by state and federal health authorities, the Australian Dental Association, the National Health and Medical Research Council and the World Health Organization.
Chlorine and fluoride chemicals are slightly acidic, so lime is added to raise the pH level of the water back to neutral, limiting the possibility of corrosion to household pipes and fittings.
Full treatment
On average, only about 10% of our water requires full treatment. Water from Sugarloaf Reservoir receives full treatment, as it is fed by water from the Yarra River. Upon leaving the reservoir, the water is fully treated at the Winneke Water Treatment Plant to National Health and Medical Research Council standards, before reaching Melbourne's domestic water supply.
Water from Yan Yean Reservoir is also fully treated as it has noticeable colour, high iron concentration and turbidity due to the nature of the soils and vegetation in the area and the shallowness of the reservoir. The Yan Yean Water Treatment Plant was completed in 1994 to overcome these water quality problems.
Full treatment includes coagulation and clarification to cause the colour and turbidity particles to settle out, filtration to remove most of the remaining suspended solids, disinfection and pH correction, sludge processing and fluoridation.
Ensuring Melbourne's water is safe to drink
New Australian drinking water guidelines were published in 2004 by the National Health and Medical Research Council and the Natural Resource Management Ministerial Council. These guidelines incorporate a new framework for managing drinking water which puts greater emphasis on prevention rather than "end product" testing to ensure water coming from people's taps is safe.
Melbourne Water is committed to ensuring the continued supply of safe, healthy drinking water and we undertake a comprehensive program of drinking water quality testing. The samples are taken from our reservoirs, aqueducts, transfer mains, service reservoirs, and points of supply to our retail water customers.
A range of parameters is examined to determine water quality. The indicator of health risks due to faecal contamination is E.coli bacteria. Our target is for 100% of samples of water supplied to our retail water customers to be free of E.coli bacteria. We consistently achieve our target, which is higher than the target required by the National Health and Medical Research Council. Results of monitoring are published in our Annual Report and on out website.
The important role of ongoing research
Our activities are supported by targeted research, and we have led a range of important research projects helping us to understand any risks associated with our water supply system, and how to manage Melbourne's water resources for the future.
While research into our drinking water quality is undertaken as part of our daily operations, we also work closely with external researchers, including the Co-operative Research Centre for Water Quality and Treatment, universities and other research organisations, to ensure that our water is safe to drink and is managed in the most appropriate way.
Planning for a sustainable future
We have to adapt better to our climate and protect our river flows and bays by making our water supplies go further. Building new dams is not environmentally or financially sustainable.
Several strategies have been developed to ensure Melbourne has sufficient water supplies to meet future needs. Melbourne Water played the leading role in developing the Victorian Government's Water Resources Strategy, which is a long-term framework for managing Melbourne's water.
The Victorian Government's Central Region Sustainable Water Strategy, which sets out actions to protect rivers and provide security of water supply to 2055, emphasises conservation and efficiency, and alternative water sources, such as re-use and recycling, aquifers, desalination, stormwater, and augmenting and interconnecting existing supply systems.
The strategy will provide 400,000 megalitres of water for urban and industrial supply, and 66,000 megalitres of water for environmental flows. The strategy does not support building new dams.
Saving water
There are many ways you can help save water. For more information on how to be waterwise visit www.ourwater.vic.gov.au
Links and other sources
Department of Sustainability and Environment - www.dse.vic.gov.au
Catchment Management - www.ewatercrc.com.au/
Consumers' guide to drinking water - www.waterquality.crc.org.au
CSIRO - www.csiro.au
EPA Victoria - www.epa.vic.gov.au
National Health and Medical Research Council - www.nhmrc.gov.au
City West Water - www.citywestwater.com.au
South East Water - www.southeastwater.com.au
Yarra Valley Water - www.yvw.com.au
Downloads
- Our Precious Drinking Water (PDF, 136kb)