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The Pipe Breaks Project

Project Number # 1091

Microbial risks from pipeline repair or renewal

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Water main renewals, repairs after main breaks, valve and hydrant repairs are a common occurrence in the water distribution networks. Renewals and repairs in this context mean all planned and unplanned interruptions (including bursts) to the drinking water supply. Such interruptions potentially breach one of the multiple barriers to prevent contamination, which is to maintain a pressurised pipe network. There is evidence in the international literature of increased microbial risk associated with mains breaks and repairs, although there is a paucity of Australian data. Currently water utilities undertake risk assessments based on qualitative factors and have limited information to quantify the risks of microbial contamination.

The industry is interested in gaining a better local understanding of the microbial risk(s) of renewals and repairs, including the impacts from current management practices. The industry is satisfied that current standard operating protocols and safety controls such as personal protective equipment protect repair and renewal crews from microbial risks, so the focus of this project is on identifying the need to improve current management practices by better understanding the microbial risk(s) to the community.


  • What is the likelihood of microbial contamination of water in the distribution system after a repair and renewal?
  • Does significant microbial contamination derive from the soil in the vicinity of the burst/repair?
  • Is it location dependent?
  • If repair crews are common (e.g. they work on both water and sewer assets) is the microbial risk different?

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