Water quality testing

Melbourne has some of the world’s best drinking water, which we test regularly to make sure it meets strict quality standards. Learn what we test for and how, or view sample water quality results.

Why we test water quality

All the water we supply, no matter where it comes from, must meet strict water quality requirements. We are regularly audited under the Safe Drinking Water Act 2003, and report all drinking water quality issues to the Department of Health each year.

Melbourne Water employee in laboratory testing water samples
Testing drinking water quality

The laws and guidelines we follow include:

Testing water quality ensures we meet these requirements. It also helps us:

  • fine-tune our water treatment processes
  • identify potential issues, like algal blooms
  • decide where to transfer water – for example, avoiding reservoirs experiencing water quality issues.

Where we test

Melbourne Water employee collects water samples at the Winneke Water Treatment Plant
Collecting water samples at the Winneke Water Treatment Plant.

Each year we test water samples from over 160 sites within our water supply network, including:

  • storage reservoirs
  • service reservoirs
  • aqueducts
  • transfer mains.

We also test water at points of supply to the retail water companies, as a final check that it meets requirements before being transferred onto homes and businesses.

What we test for

We test for a number of parameters, including:

  • clarity (turbidity)
  • minerals and natural substances like iron and manganese
  • colour
  • pH
  • bacteria, such as E. coli
  • chlorine and fluoride levels
  • contaminants like fuel and pesticides.

Natural variations

Did you know the colour, taste and smell of your water can change throughout the year? This is very normal and usually depends on a number of factors:

  • where your water comes from, as each reservoir has natural differences in colour and mineral content
  • demand – people use more water in summer, which causes it to travel faster through the pipes
  • water temperature, with cooler water generally tasting better.

Water quality data – 2020-21 analysis

The following data represents a typical analysis of Melbourne’s drinking water quality. This is based on testing results from our major storage reservoirs, once water has been through the primary treatment process.

Please note:

  • all parameters are measured in milligrams per litre unless otherwise noted
  • values are rounded to the nearest decimal point.
​Parameter/ source Cardinia Greenvale Silvan Winneke Tarago​
pH (units)​ 7-7.6 7-7.8 6.7-8.0 6.9-7.5 7.1-7.6
Colour (Pt/Co)​ 0-5 2-7 4-14 0-2 0-5
Turbidity​ (NTU) 0.4-0.7 0.74-1.4 0.7-2.1

0.1-0.27

0.1-0.27
Electrical conductivity (uS/cm)​ 61-126 61-71 44-64 109-121 136-156
Iron 0.01-0.05 0.005-0.12 0.05-0.14 0.004-0.04 0.001-0.01
Manganese ​0.001-0.005 ​0.001-0.008 0.004-0.02 0.001-0.005 0.001-0.04
Fluoride​ 0.4-0.94 0.1-0.87 0.1-0.9 0.22-0.96 0.1-0.95
Aluminium 0.013-0.028 0.034-0.085 0.04-0.13 0.02-0.061 0.012-0.055
Arsenic​ <0.0003 <0.001​ <0.001​ <0.001 <0.001
Boron​ 0.1-0.2 0-0.02 0-0.06 0-0.04 0-0.01
Bromide​ <0.05 <0.05 <0.05 <0.05 <0.05
Cadmium​ <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
Calcium​ 6.3-7.9 3.7-4.3 2.4-5.3 6.7-8.8 8.6-10.8
Chloride 5-7 8-11 7-8 16-19 24-26
Chromium <0.001 <0.001 <0.001 <0.001 <0.001
Copper​ 0.01-0.02 <0.01 <0.01 <0.01 <0.01
Chloroacetic acid​ (ug/l) <3 <3 <3 <3 <3
Dichloroacetic acid (ug/l) 3 3-4 14-15 3-4 7-8
Trichloroacetic acid​ (ug/l) 3 2-4 10 2 6-7
Hardness​ 18-23 15-17 11-18 25-31 31-38
Lead​ <0.001 <0.001 <0.001 <0.001 <0.001
Magnesium​ 0.65-0.89 1.29-1.53 1.02-1.63 1.84-2.16 2.29-2.75
Mercury​ <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
Nickel​ <0.001 <0.001 <0.001 <0.001 <0.001
Nitrate​ 0-0.068 0.093-0.165 0.181-0.306 0.303-0.458 0.393-0.474
Potassium​ 0.38-0.45 0.54-0.66 0.53-0.67 1.09-1.38 1.83-2.13
Silica 2.9-4.0 4.3-6.8 5.9-8.0 4.4-8.3 11.1-14.9
Sodium​ 3.9-5.8 4.8-6 3.6-5.2 8.7-10.7 11.9-14.9
Sulphate <1.5 1.5-1.8 1.5-1.8 10.8-12.9 2.1-2.7
Total alkalinity as CaCO3​ 19-24 12-14 10-15 11-13 13-32
Total organic carbon​ 1.0-1.5 1.3-1.4 1.3-1.8 1.0-1.8 1.9-2.2
Total phosphorus​ 0.005-0.015 0.005-0.013 0.005-0.01 <0.005-0.014 0.014-0.045
Total dissolved solids​ 34-70 34-41 24-35 60-67 75-86
Trihalomethanes 0.013-0.036 0.013-0.073 0.028-0.080 0.019-0.039 0.041-0.073
Zinc​ 0.001-0.002 0.002-0.005 0.003-0.006 <0.001 <0.0003-0.0005
Last updated:
18 August 2021