UPDATE 11: All drinking water must be boiled in Martinborough until further notice

4.00pm, 11 February 2019

Following the boil water notice issued on Friday 1 February, South Wairarapa District Council continues to advise that all drinking water from the Martinborough town supply must be boiled before being used for drinking, making up formula, juices and ice, washing fruits and vegetables, other cooking needs, or brushing teeth.

Safe drinking water continues to be available to the public from the emergency water bladders behind the Waihinga Centre, outside the Wharekaka aged-care home, Martinborough School, the golf club and rugby club. The bladders will stay in place until the boil water notice is lifted.

Wellington Water is coordinating the actions required to get the boil water notice lifted. Experts have been systematically checking the water supply network – from the source, at the bore; the treatment plant; the pipe supply network; through to the reservoirs. This work includes checking all the backflow mechanisms on private connections to the water network.

While undertaking a risk assessment of all the possible causes of contamination, an in-depth review of past data has revealed that, a temporary malfunction of the UV disinfection system is the most likely cause of this event. The UV disinfection system is designed to kill 99.9% of bacteria entering the water network. Work has started to fully check and fix the UV system to ensure this cannot happen again. At the weekend, two of the reservoirs were emptied, thoroughly cleaned and disinfected with chlorine; the final two are being done now. All test results since the chlorination of the reservoirs and the area east of Todds Rd on 4 February have been clear of E. coli.

The next step is to flush the whole network with water. The timing of this, and what it means for residents, will be communicated later this week; however it is likely that network flushing will cause some discolouration of the water. Residents may need to run taps until the water runs clear.

Once flushing is completed, clear test results on three consecutive days are required before the Council will consider lifting the boil water notice. This will be done in consultation with Regional Public Health.

“We, again, apologise for the inconvenience caused to the people and businesses of Martinborough. Please offer information and help to an any neighbours who may not have access to the internet, or who may need some help gaining access to safe drinking water.

“Now that we have an understanding the likely cause of contamination, we can have more confidence that we’re taking the right steps to prevent it from happening again.

“Once flushing is complete and Regional Public Health is satisfied that we’ve taken all the necessary steps, we’re feeling confident of getting further clear results and the boil water notice being lifted shortly,” says Ms Napier.

The risk of getting sick from drinking the water during the period leading up to the notice being issued is low but possible, especially for vulnerable people. Babies, young children, pregnant women, the elderly and people who have weakened immune systems would have been more at risk of illness. If you develop an illness with diarrhoea, vomiting and/or a fever, and are concerned about your health, get advice from your doctor or contact Healthline (0800 611 116).  Any illnesses developing after a three-week period are unlikely to be related to drinking potentially contaminated water.

Next update: 4pm Tuesday 12 February, or earlier if required.

ENDS

This is what we know so far:

- Late afternoon on 30 Jan, routine testing carried out at various sites around the water system showed a positive result for low levels of E. coli at Martinborough School, all other samples were clear.

- Within half an hour, Regional Public Health was contacted to discuss the course of action.

- In consultation with Regional Public Health, the school was advised to use an alternative water source as a precaution.

- Further samples were taken from around the system and sent for testing, and follow-up results received on 10am 31 Jan showed all the results were clear. This was communicated to the school and in a Facebook response.

- Continued testing showed a second low, positive result for the sample taken near the reservoir

- In conjunction with Regional Public Health, the Council issued a Boiled Water Notice (3pm 1 Feb) before confirmation of the result was received over the weekend.

- Results from the samples taken on Friday and Saturday morning showed no alerts for E. coli in the samples taken in the town but confirmed the low, positive result for E. coli for the sample taken near the reservoir.

- In consultation with Regional Public Health, the Council developed a plan to chlorine flush the reservoir area of the system East of Todds Rd. This chlorine disinfection of Todds Rd was completed 6.30pm on 4 February.

- Test results from the samples taken before the chlorine disinfection confirmed low-level E. coli contamination of the reservoir as well as the water network east of Todds Rd. All results in the town were again clear.

- On 7 February, Council received clear test results for samples taken post-chlorination at the reservoir, east of Todds Rd, and the main pipe into town, as well as at sites within the town. These results suggest that chlorination has cleared the contamination; however, there is ongoing work to identify the probable source of contamination to prevent this happening again.

- On 8 February, clear test results were received for samples taken one-day post, targeted, chlorination of the reservoir and the area east of Todds Rd. This includes for those areas within the chlorinated zone and throughout the water network, indicating the contamination has been cleared.

- On 11 February, a temporary malfunction in the UV disinfection system has been identified as the most likely cause of contamination.

- Currently reported levels of illness are not above that expected at this time of year. Wairarapa DHB has reported no presentations at ED in association with this event.

How to boil water for drinking:

  • Boiling will kill all disease-causing organisms.
  • Bring water to a rolling boil (where bubbles appear in the centre and do not disappear when the water is stirred) for one minute or boil a full electric jug until it switches off
  • Cool water (do not use ice cubes to do this) and pour into clean container with a lid
  • Refrigerate until needed.

For more information, contact SWDC on 06 30 69611 at or visit swdc.govt.nz/martinborough-town-water-situation further information about this issue, including past updates, FAQ, and educational resources.

Media contact:

Amy Wharram, Communications Manager 027 252 2863

South Wairarapa District Council