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Drinking-Water Management Current Issues Update 1


Update 1 - September 2016

As you may be aware Hastings District Council and Hawke’s Bay Regional Council have been confronted with an aquifer contamination effecting Havelock North’s water supply, which will now be the subject of a National Inquiry. Water NZ will support this inquiry but in the meantime is in a position to share knowledge and be a thought leader on issues as they evolve from Havelock North throughout the water industry.

In order to achieve this knowledge sharing and thought leadership we intend to release a regular update to our members. These will be brief and informative.

Water NZ is an industry association whose aim is to support its member’s delivery of 3 waters services to New Zealand. Water NZ is in a unique position to understand issues and share knowledge for the benefit of all members.

Learning’s from Havelock North

At a high level the events at Havelock North to date are:

  • E.coli presence in Havelock North bores 1 & 2 confirmed on 12 th August from a sample taken on 11 th August
  • On the 12 th August after consultation with District Health Board it was agreed to initiate chlorine dosing immediately and a boil water notice was issued not long after.
  • Havelock North’s bores were turned off and supplied via Hastings on the 24 th August
  • A reticulation flushing regime was started on the 25 th August.
  • The boil water notice was lifted on the 3 rd September.

Very early on in the contamination event the primary concern moved from a bacterial or viral risk to a potential protozoa risk as the bores could no longer be deemed to be supplying water from a secure ground water source, hence the boil water notice.

E-coli are used as an indicator of risk. If E-coli are present then there is a good chance other pathogenic bacteria, viruses or protozoa could also be present. Presence means a count greater than zero. In Havelock North’s case the highest E.coli result was >23/100ml (maximum reporting limit) on one occasion only with all other days having results less than 23/100ml.

E.coli results of greater the 23/100ml are common in many rain water supplied systems or other previous national contamination incidents. The infectious dose for campylobacter can be anywhere between 500 – 9000 organisms. In Havelock North’s contamination event the presence of E.coli indicated that campylobacter was present in far greater numbers than E.coli.

Here lies a water industry challenge for managing the public health risks and how we manage our ground water sources.

Some of the topics we intend to be covering are the current requirements for:

  • Sanitary surveys of bores
  • Secure ground water status as defined by the NZDWS
  • Routine and Preventative operations and maintenance – people, process and equipment
  • Monitoring and compliance
  • Possible Emergency Response options (Water Safety Plans – Risk Management)
    • Emergency chlorine dosing
    • Flushing plans
    • Media plans
    • Assistance
  • Interaction with other agencies to ensure we have safe water supplies and the roles of respective agencies; who takes a lead in these situations?
  • Monitoring chlorine demand through the network.
  • The national inquiry information as it unfolds

The following public forum has been created for members to provide comments and their experiences.

http://forum.waternz.org.nz/index.php?sid=e9fdf326a4f37e3bfbd76b1321837aa4

Regards
Noel Roberts
Technical Manager
Water New Zealand