Reticulated Water – Testing Regime
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WRITTEN QUESTIONS
11th Assembly
02/09/2010
192. Reticulated Water – Testing Regime
Mr Elferink to MINISTER for Essential Services
QUESTION
ANSWER
Answered on 12/11/2010
Question 1.
Q What are the current guideline levels used by Power and Water to indicate coliform contamination?
A The Australian Drinking Water Guidelines are utilised for monitoring microbiological water quality. These Guidelines specify that at least 98% of samples collected from the reticulation system should be absent of Escherichia Coli (E.coli).
Question 2.
Q On how many occasions during 2008, 2009 and 2010 did monitoring of the reticulated water supply in Darwin and Palmerston indicate levels of coliforms above the guideline level?
A None
Question 3.
Q What were the locations of those above guideline results?
A There were no “above guideline” results.
Question 4.
Q What steps were taken to identify and address the above guideline results?
A a) Steps taken to identify -
b) Response to any ‘above guideline’ results –
WRITTEN QUESTIONS
11th Assembly
02/09/2010
192. Reticulated Water – Testing Regime
Mr Elferink to MINISTER for Essential Services
QUESTION
- Coliforms are used in operational monitoring of water distribution systems to indicate inadequate treatment, breakdowns in system integrity or the presence of biofilms:
1. What are the current guideline levels used by PowerWater to indicate coliform contamination.
2. On how many occasions during 2008, 2009 and 2010 did monitoring of the reticulated water system in Darwin and Palmerston indicate levels of coliforms above the guideline level.
3. What were the locations of those above guideline results.
4. What steps were taken to identify and address the above guideline results.
ANSWER
Answered on 12/11/2010
WRITTEN QUESTION NUMBER 192
REPLY TO MR ELFERINK FROM MINISTER FOR ESSENTIAL SERVICES
Question 1.
Q What are the current guideline levels used by Power and Water to indicate coliform contamination?
A The Australian Drinking Water Guidelines are utilised for monitoring microbiological water quality. These Guidelines specify that at least 98% of samples collected from the reticulation system should be absent of Escherichia Coli (E.coli).
Question 2.
Q On how many occasions during 2008, 2009 and 2010 did monitoring of the reticulated water supply in Darwin and Palmerston indicate levels of coliforms above the guideline level?
A None
Question 3.
Q What were the locations of those above guideline results?
A There were no “above guideline” results.
Question 4.
Q What steps were taken to identify and address the above guideline results?
A a) Steps taken to identify -
- The presence of E.coli in drinking water supply systems is determined by laboratory analysis of water samples.
Across the reporting periods 2007-2008, 2008-2009 and 2009-2010 approximately 2,000 water samples were collected from the Darwin and Palmerston water supply distribution system.
Samples are analysed at the Department of Resources Microbiological Laboratory in Darwin.
b) Response to any ‘above guideline’ results –
- No above guideline results have been identified.
A positive result has been detected on three occasions from approximately 2000 samples (Hydrant at East Arm Port in May 2008 and March 2010 and Rapid Creek sample site in December 2008)
A positive E.coli detection in any sample triggers an immediate review of all bacteriological results from other sites sampled on the same day. Based upon available evidence a response would be formulated and executed by operational personnel. The circumstances and the operational response are communicated to an established contact officer in the Department of Health and Families.
Such a response may involve a combination of actions including site inspection, re-sampling, field confirmation of chlorine residuals, manual dosing of chlorine and flushing of water mains.
Last updated: 04 Aug 2016