Posted by Jason Colton - Chief Technology Officer.July 3rd 2019
The Ministry of Health (MoH) published the Annual Report on Drinking-Water Quality on June 27th 2019. The report covers the period July 1st 2017 to June 30th 2018 meaning it’s a year out of date already. What it shows it that compliance with the Drinking-water Standards of New Zealand 2008 (DWSNZ) significantly decreased in the 2017-2018 reporting period compared to the previous year. The MoH have been promoting a positive message with the publication of the report but is this the right message to send to consumers? Lets take a closer look at the number of people being supplied with non-compliant water.
People are being supplied with water that does not comply with the DWSNZ. That’s an increase of 287,000 people from the previous year.
People are being supplied with water that does not comply with the bacteriological requirements of the DWSNZ. This is an increase of 176,000 from the previous year. *The figure quoted in the in the annual report (and subsequently in the media) for bacteriological compliance is 97.7% of the population which equates to 88,297 people. However the more detailed data breakdown supplied in Tables 4-7 of the report adds up to 322,000 which equates to 91.6% of the population being supplied with compliant water.
People are being supplied with water that does not comply with the protozoal requirements of the DWSNZ. This is an increase of 359,435 from the previous year.
People are being supplied with water that does not comply with the chemical requirements of DWSNZ. This is a reduction of 54,440 from the previous year.
A lot of the public facing messaging was around the vulnerabilities of small supplies. Whilst this is a known issue, particularly in tourist destinations, the use of percentage compliance figures can be misleading. The following table shows the number of people supplied with non-compliant water from different supply sizes. It can be seen that the majority of people supplied with water non-compliant with the bacteriological and protozoal requirements of the DWSNZ are served by large supplies.
We are 3 years on from the Havelock North event and yet over 1 million people are still receiving water that does not comply with the drinking water standards. Currently a large number of councils are investing significantly in water supply and are working very hard to achieve full compliance. Hopefully the transition to reporting based on the Drinking Water Online system will mean the industry and consumers can see the service level outcomes of this work far more rapidly in the future.