News

Inside TasWater - Episode 9

8 May 2019

TasWater carries out a range of maintenance activities to ensure the reticulated water meets both the requirements of the Australian Drinking Water Guidelines and the aesthetic requirements of our customers.

One of these maintenance activities is called flushing. Flushing is when water is released from a fire hydrant or access point at a set flow rate to clean the water mains. Water is released and tested until it either returns to a clear appearance or the turbidity levels are within the Australian Drinking Water Guidelines. 

Flushing can occur whenever it is needed but is most common after large water outages. The change to the flow rate within the pipe can stir up natural sediment. Flushing programs are planned around customer feedback, water sampling and historical data to ensure we reach areas that it is needed most, and an example is dead ends where the water does not circulate as much. 

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A weekly program is conducted in Hobart at a well-known factory to ensure any build-up of natural sediments does not affect their production. TasWater recently stepped through the process as TasWater Water Services Operator, Danny Cleaver completed the work.

Danny uses a field testing kit to test levels of chlorine and turbidity when arriving on site.   Levels read at 0.92 for turbidity, with a chlorine reading of 0.3 parts-per-million (ppm). Flushing is continued for another couple of minutes before another test is completed, with a new turbidity level of 0.61 and chlorine reading of 0.2ppm.   

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This can take anywhere between five minutes to two hours.  Chlorine levels can be hard to achieve at times due to chlorine dissolving in pipes after being added at the bulk stage. If this is the case chlorine is then added into the reticulation system at the reticulation reservoirs. Water from flushing is not returned to the drinking water system. It is therefore directed into storm water drains and eventually returns to environment.

In some other areas in the South of the state TasWater does have an automatic flushing system in place.  Sorell, for example, has an old water tank which is used to store water after it has been flushed through the system. This stored water is then used for irrigation purposes.

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Water is a limited resource that must be carefully managed to ensure there is enough for the state’s growing population and environmental needs. Flushing is critical to maintaining high-quality drinking water and TasWater ensures that sediment is removed using the least amount of water as possible. Crews do consider water reservoir levels prior to undertaking a flushing program and where possible avoid summer months and total fire ban days.

At the start of 2019 TasWater commenced rolling out automated flushing systems state-wide to areas known to have a high amount of natural sediment build up. These systems can be controlled remotely by an app and can be scheduled to commence a flush on a specified date and time.

TasWater’s Customer Contact Centre found that some of these systems are generating leak reports as customers can hear water running.  Residents that live near automated flushing systems are being notified via letter.

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