Council staff routinely monitor raw and treated water physical and chemical parameters as part of daily operational practise.
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 less than 1ntu | 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.
Water Samples
Please note these results are examples only to provide a comparison between different raw and treated water supplies.
Samples from Dalby Water Supplies
The Dalby scheme is primarily a groundwater (bores) scheme with peak demand and emergency back up provided by surface water (Condamine River).
Raw Water (untreated) Supplies
|
A Alluvial Bore
requires no treatment prior to drinking
|
Condamine River Water
requires treatment prior to drinking
|
| Ph | 7.6 | Ph | 7.2 |
| TDS | 536 | TDS | 146 |
| Conductivity | 1,072 | Conductivity | 292 |
| Turbidity | <1 | Turbidity | 30 |
| Hardness | 143 mg/L | Hardness | 62 mg/L |
| |
Dalby's surface water supply (Condamine River) undergoes a Floculation Treatment Process to make it suitable to drink.
|
|
B Alluvial Bore
requires treatment prior to drinking
|
Coal Seam Methane By-Water
requires treatment prior to drinking
|
| Ph | 7.6 | Ph | 8.4 |
| TDS | 1,860 | TDS | 3,600 |
| Conductivity | 3,720 | Conductivity | 8,660 |
| Turbidity | 0.2 | Turbidity | 6.5 |
| Hardness | 403 mg/L | Hardness | 46 mg/L |
| Dalby's B Alluvial Bores undergo a Desalination Process to make it suitable to drink. | Council is in the process of building a second desalination plant to treat the Coal Seam Methane By-water. |
For more information please check out the Regional Water Supplies page.
Treated Water (drinking) Supplies
|
Town Tap Water
| The water supplied to town is a combination of all three water supply sources, A alluvial bores, desalinated water and treated river water, when available. The results displayed can differ depending upon the mix of water used. This is why a rigorous and regular testing regime is conducted to ensure the all the water supplied to town meets the Australian Drinking Water Guidelines (ADWG). |
| Ph | 7.8 |
| TDS | 583 |
| Conductivity | 1,160 |
| Turbidity | 1 |
| Hardness | 124 mg/L |
|
RO* Permeate Water
(after desalination process)
|
The drinking quality water which is produced after the desalination process using Reverse Osmosis technology is called Permeate. As displayed the pH of Desalinated water is not within the ADWG of 6.5 - 8.5 therefore the water undergoes a further process of aeration to remove carbon dioxide in solution thereby improving the pH. For more information on the Desalination process please check out the Water Treatment Processes page.
|
| Ph | 5.6 |
| TDS | 53 |
| Conductivity | 123 |
| Turbidity | n/a |
| Hardness | 41.6 mg/L |
* RO - Reverse Osmosis
|
RO Reject Water
(after desalination process)
|
The desalination process produces two products, a permeate stream (drinking water) and a highly concentrated salty stream (reject water). Approximately 20% of water is wasted in the concentrate stream along with the rejected salts. This stream is either used for filter backwashing or is sent to the evaporation ponds.
|
| Ph | 8 |
| TDS | 1,650 |
| Conductivity | 3,300 |
| Turbidity | n/a |
| Hardness | 10,400 mg/L |
Water samples from other regional supplies will be added for comparsion.
For further information please contact Council's WaterWise Officer on (07) 4669 9044.
Water Quality 