Water Quality

Council staff routinely monitor raw and treated water physical and chemical parameters as part of daily operational practice.

To ensure compliance with the Australian Drinking Water Guidelines, water samples taken by Council staff are delivered to Queensland Health and Scientific Services NATA accredited laboratories for analysis.

Water Quality

The appearance, taste, odour, and ‘feel’ of water determine what people experience when they drink or use water and how they rate its quality.

Water Quality Monitoring

The measurable characteristics that determine these largely subjective qualities are:

  • true colour (i.e. the colour that remains after any suspended particles have been removed)
  • turbidity (the cloudiness caused by fine suspended matter in the water)
  • hardness (the reduced ability to get a lather using soap)
  • total dissolved solids (TDS)
  • pH
  • temperature
  • taste and odour
  • dissolved oxygen.

Colour and turbidity influence the appearance of water.

Taste can be influenced by temperature, TDS, and pH.

The ‘feel’ of water can be affected by pH, temperature, and hardness.

Rates of corrosion and encrustation (scale build-up) of pipes and fittings are affected by pH, temperature, hardness, TDS and dissolved oxygen.

In general, the physical characteristics of water are not of direct public health concern, but they do affect the aesthetic quality of the water, which largely determines whether or not people are prepared to drink it. If water is unpalatable or appears to be of poor quality, even though it may be quite safe to drink, the consumer may seek other water sources that may not be as safe.

Each guideline value is set at a level that ensures good quality water – that is, water that is aesthetically pleasing and safe, and that can be used without detriment to fixtures and fittings.

The values are determined by considering water quality guidelines used by other countries and international bodies, assessing any health implications and then deciding on a point beyond which the quality of the water might no longer be regarded as good.

Factors taken into account include:

  • taste and odour thresholds (i.e. the smallest concentration/amount that would be just detected by a trained group of people)
  • the concentration or amount that would produce noticeable stains on laundry or corrosion and
    encrustation of pipes or fittings
  • the concentration or amount that would be just noticeable in a glass of water and lead to a perception that the water was not of good quality.

Australian Drinking Water Measures

The Australian Drinking Water Guidelines contain a wide range of of values for physical and chemical characteristics. The five characteristics listed below are only a few of the measurable characteristics.

Factor Measure Health limit Aesthetic limit Notes
pH unit * 6.5 – 8.5 an expression of the intensity of the basic or acid condition of a liquid
Conductivity us/cm not necessary <1000 conductivity is similar to TDS. The equivalent figure in electrical conductivity units (EC units) can be roughly determined by doubling this value
Total Dissolved Solids (TDS) milligram/litre not necessary <500 500 – 1,000mg/L is acceptable based on taste, > 1,000 unsatisfactory taste.
Hardness milligram/litre not necessary 60 – 200 but <500 To minimise a build up of scale in hot water systems/kettles, total hardness in drinking water should not exceed 200mg/L
Turbidity NTU Nephelometric Turbidity Units # 5 ntu to <1 ntu The cloudiness of the water caused by the presence of fine suspended matter, like clay, silt etc.

* While extreme pH values (< 4 and > 11) may adversely affect health, there are insufficient data to set a health guideline value.

# insufficient data to set a health guideline value

Information sourced from: Australian Government, National Health and Medical Research Council, Australian Drinking Water Guidelines 6, 2004.