Council strives to supply clean safe drinking water at all times, though occasionally cases of discoloured water occur.
Occasionally residents may experience discoloured water, below are some details about what causes discoloured water and what to do if you experience this.
Discoloured Water has two main triggers as follows:
- The most common case is that a number of residents in the summer months experience discoloured water coming through their household system, the result of manganese or iron being removed from the inside wall of pipework. Manganese or iron are trace elements which are soluble in water, but can also come out of solution and accumulate inside pipework.
- Occasionally after very heavy rain upstream of Bathurst, the river water quality gets so bad that the treatment plant is unable to produce water to the usual high standards of clarity. This continues until the quality of the river water improves, and the clean water makes its way through the system.
Why does it occur?
Bathurst has had reticulated water for over 120 years and while the system largely works very efficiently, at times discoloured water can be an issue. Discoloured water in hot weather is usually caused by Manganese which is common in many drinking water supply systems in Australia. In Bathurst, the soils in our catchments contain manganese and some iron which is very difficult to remove completely during the treatment process.
Over time the manganese is deposited on the walls of pipe work where it normally stays in a biofilm unless disturbed. Consequently, it is worse where the pipe work is older.
Manganese can be disturbed when the flow (speed) of water in the pipe is increased. This increase can be due to a water main break, a shutdown for maintenance, a large demand on the water supply due to a fire or high water demand due to warm or hot weather.
What can Council do?
Council flushes water mains as a maintenance measure to reduce the incidence of discoloured water, especially during summer, however it is not possible to predict where discoloured water will occur. Also, as Council is keen to conserve water and not be wasteful, flushing is limited to essential cases. Current technology is also limited in its ability to remove the manganese from the water supply system, however improvements are constantly being made, and when a suitable solution is available, it will be adopted as Council is keen to minimise this problem.
What can you do?
If you encounter discoloured water during working hours you should call Bathurst Regional Council on 02 6333 6100. If the discoloured water occurs after hours call Council’s emergency number 6334 2795. Council staff will normally advise to run the tap closest to the street and another tap furthermost from the street for no more than 5 minutes. If possible, the water should be put to good use on the lawn or garden (either using a bucket or hose to see if the discolouration clears). In many cases, this will clear the problem. The cost to the customer of this flushing is on average between 10 and 20 cents. If the water is still discoloured after this time, the same number should be called and arrangements will be made to send a crew to your street and flush the water main, and the service if necessary. Once these have been flushed you may need to run your taps individually to clear any residue.
Is the water safe to drink when discoloured?
Council carries out weekly water quality testing and whilst discoloured water may appear unpleasant, the water quality tests show discoloured water is safe to drink and is not a hazard to health.
Discoloured water does not cause stomach upsets or diarrhoea.
Mild or moderate cases of dirty water usually only pose aesthetic concerns and the water remains safe to drink. Examples of water safe to drink are shown in the following photos:
What do I do if I need to wash?
If you think you might have discoloured water you should check the colour of the water before washing clothes. Do not wash until the water is clear.
It is especially important to check the colour of the water before the final rinse cycle as this is the time when clothes can be stained. Avoid using oxidising agents such as laundry bleach as these products may intensify staining where any elements present may form a solid and will stick to the clothing fibres.
If your load of washing is dirty or stained, you should keep the washing completely wet, and not hang it out.
Some washing powders cause the pH level of the water in the washing machine to increase, and this has the effect of causing manganese or iron in the water to come out of solution and to stain the washing. Also, powders high in phosphorus can also have the same effect.
When the water has cleared then rewash using a good quality liquid dishwashing detergent and white vinegar as they can also help remove dirty water stains.
Council has completed extensive trials to remove Manganese from the water which is treated at the Water Filtration Plant.
The Bathurst Water Filtration Plant (WFP) treats water released from the Macquarie River for distribution to consumers in the Bathurst Region. The basic filtration processes at the WFP comprise of the addition of alum and polymer to the raw water for coagulation, flocculation, sedimentation, gravity sand filtration, chlorination disinfection, pH control and fluoridation.
Powdered activated carbon (PAC) is also dosed to the raw water periodically for taste, odour and toxin removal due to the presence of algae in the raw water. Manganese is a compound naturally occurring in river water; it does not create any public health concerns but is unsightly as the colouring will often turn the filtered water to varying shades of black. The soil in the catchments above the Bathurst Water Filtration Plant is naturally rich in manganese.
The WFP was designed to consistently produce water which complies with the current Australian Drinking Water Guidelines. However, due to limitations with the plant design (in that not enough contact time can be provided), the existing potassium permanganate dosing plant cannot cope with the manganese problem associated with the feed water. Councils’ objective is to determine an alternative method of removing the manganese from the raw water.
In June 2011, Council requested NSW Public Works to undertake specific investigations on Council’s behalf into potential Manganese removal methods which had been successful in other areas where the feed water was similar to that in Bathurst. The result was that NSW Public Works prepared a proposal for Council which covered a three stage trial. Stage 1 of the trial has been completed.
Stage 1 of the pilot plant trial has involved the construction of a replica filter which functions in the same way as the 14 filters operational at the WFP. The replica filter is being used to dose chemicals to determine the most effective method of oxidising the manganese in the raw water. Different parameters such as water temperature, PH levels, turbidity and residual chlorine levels have been included to ensure that the test dosing takes into consideration the changing attributes of the feed or raw water.
Early results have been very positive and indicate that a high level of manganese removal will be possible by dosing sodium hypochlorite to the settled water prior to filtration.
A stage 2 trial utilising one of the existing 14 sand filters at the Water Filtration Plant has been completed during 2012. This yielded positive results and confirmed the improvements identified in the Stage 1 trial.
What's happening next?
Based on the success of the Stage 1 and 2 trials Council has developed a concept design to roll out the chemical dosing methodology across the entire Water Filtration Plant.
Subsequently a detailed design has been prepared and completed. In addition this has been further advanced to enable the completion of tender documentation with tenders having being called in November 2013 and closing 17 December 2013.
It is anticipated that a report to Council recommending to accept a tender offer will be considered at the February 2014 Council Meeting.