Water Quality and Treatment
Water quality
Melbourne Water is committed to ensure the continued supply of safe, healthy drinking water and we undertake a comprehensive program of drinking water quality testing. About 50,000 tests are carried out every year on samples from 160 sites. 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 (NHMRC). Results of water quality monitoring are published in our Annual Report.
Water treatment
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
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 and the Maroondah Aqueduct. Upon leaving the reservoir, the water is fully treated at the Winneke Water Treatment Plant to NHMRC 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
- pH correction
- Sludge processing
- Fluoridation.
Downloads
- Sugarloaf Pipeline Drinking Water Report (PDF, 937kb)
You will need Adobe Acrobat to access the above PDF documents. 