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3% improvement in drinking-water quality for 2004

Media Release

21 March 2006

Ministry of Health review of drinking-water quality during 2004 finds 3% improvement

New Zealanders living in large towns and cities continue to have access to tap water which meets the national standards for drinking-water quality.

Overall there was a three percent increase in the numbers of people who were supplied safe drinking-water during 2004, however smaller communities with smaller water supplies are still less likely to access drinking-water that complies with the standards.

The findings were released today by the Ministry of Health in the Annual Review of Drinking-Water Quality in New Zealand 2004.

The review assessed the microbiological health risk in water against two criteria: Escherichia coli bacteria and the water born protozoa Cryptosporidium. It also looked at the chemical composition of drinking-water.

During 2004 water supplied to 74 percent of the New Zealand population complied with the E. coli criteria for drinking-water standards, a three percent improvement when compared to the previous year. There was also a 71 percent compliance with the Cryptosporidium criteria of the standards, which is a 7 percent improvement since 2003. That represents another 120,000 people who have access to good quality drinking water.

Approximately 1.04 million New Zealanders were supplied during 2004 with water that either failed to comply bacteriologically with the DWSNZ:2000 drinking-water quality standards or their water was self supplied.

The causes of the non-compliance centred for the most part on levels of E coli or a failure by water suppliers to take appropriate action, including monitoring after it had been found. Some took insufficient samples during the year to demonstrate E. coli compliance and other water suppliers did not use accredited labs for testing, or supplied water from an unregistered source.

The Ministry of Health's Principal Public Health Engineer Paul Prendergast says 1.04 million people did not necessarily receive unsafe drinking-water during 2004. It simply means water suppliers did not demonstrate the water was safe.

"Most of the non-compliant supplies were from small rural water supplies or domestic supplies that were either not monitored or inadequately monitored," he says.

The review also found that four hospitals or health services that were not connected to municipal drinking-water supplies, failed to comply bacteriologically with the drinking-water standards. In two of the cases the water supplier failed to take corrective action following the discovery of E. coli. And the other two cases had water supplies that were inadequately monitored. One of these has improved drinking-water monitoring since the review and another has since connected to the town supply.

Some school drinking-water also needs improvement. During 2004, 57 percent of the 640 schools with their own water supplies conducted some bacteriological monitoring, this is a two percent improvement on 2003. Of the school water supplies monitored, 84 or 13 percent complied with the bacteriological criteria of the drinking-water standards, a one percent reduction compared to the previous year.

"The quality of drinking water is an important factor in maintaining public health. If we fail to maintain high microbiological standards there is the potential for outbreaks of disease," Mr Prendergast says.

Contaminated water can spread a range of gastrointestinal disease. These are caused by bacteria, viruses, or protozoan parasites including Cambpylobacter, Salmonella, E. coli O:157, Giardia, Cryptosporidium, Norwalk virus and other enteric viruses. Other diseases can include hepatitis A and dysentery.

Copies of the Annual Review of Drinking-Water Quality in New Zealand 2004 are available on the Ministry of Health website:


Questions and Answers

How was the information obtained?
The information about the quality of drinking-water was obtained through the public health units of District Health Boards using questionnaires on the performance of water suppliers. The survey gathered information on both distribution zones and water treatment plants and the results were verified with the water suppliers before they were sent in.

What is a registered water supplier?
The Ministry of Health maintains a register of all water suppliers that it is aware of that serve 25 people or more for at least 60 days each year. Water suppliers fall into two groups: local authorities and private organisations or communities responsible for the operation of their own drinking-water supplies. The register of suppliers includes town and rural water supplies, food outlets, schools, marae, sports clubs, hospitals, hotels, motels and camping grounds.

In 2004 the Register of Community Drinking-Water Supplies in New Zealand (The Register) contained 2,211 distribution zones and 2,156 water treatment plants and covered an estimated 89 percent of the New Zealand population. The microbiological and chemical quality of drinking water was assessed against the DWSNZ:2000 standards, using a survey of all treatment plants and distribution zones.

What are the DWSNZ:2000 standards?
The Drinking-Water Standards for New Zealand 2000 replace the 1995 standards. They detail how to assess the quality and safety of drinking-water which is intended to be used for human consumption, food preparation, utensil washing and personal or oral hygiene. The standards list the maximum concentrations of chemical, radiological and microbiological contaminants acceptable for public health in drinking-water. For community drinking-water supplies the standards also outline the required water sampling protocols that must be observed. New drinking-water standards 2005 have recently been published and come into effect on December 31st. They'll be used to assess drinking-water in 2006.

Why is the Ministry of Health concerned about drinking-water quality?
The microbiological quality of drinking-water is an important factor in maintaining public health. Failure to maintain high microbiological standards by not managing bacteria and viruses leads to the potential for outbreaks of disease if the water becomes contaminated by pathogens that the community has not become immune to. Although the local community may become acclimatised to the presence of micro-organisms that are regularly present in the water and develop a resistance to them, visitors to the area may be affected.

What other activities are underway to improve the quality of drinking water?
The Annual Review of Drinking-Water Quality in New Zealand 2004 is part of an organised campaign that started in 1992 to improve the quality of the country's drinking-water. The review covers the third year that the microbiological and chemical quality of drinking-water was assessed using the Drinking Water Standards for New Zealand 2000 (DWSNZ:2000). Other ways New Zealand's drinking-water safety has been developed since 1993 are:

- The Drinking-Water Standards for New Zealand 1995 and 2000

- The new Drinking-Water Standards for New Zealand 2005

- External surveillance by health Protection Officers

- A Register of Community Drinking Water Supplies

- Public Health Grading of Community Water Supplies

- An Annual Report on the Microbiological and Chemical Quality of Drinking Water Supplies in New Zealand

- Guidelines for Drinking Water Quality Management in New Zealand

- Register of Ministry of Health Recognised Laboratories for drinking-water compliance testing

- Laboratory accreditation requirements for all testing laboratories

- National electronic water quality information database (WINZ)
Public Health Risk Management Plans for drinking-water supplies

What is the status of Public Health Risk Management Plans?
Forthcoming legislation is expected to require each water supply to be covered by a quality assurance programme contained in a public health risk management plan. There is currently no legal requirement for water suppliers to have a public health risk management plan in place, but they are advisable and by the end of 2004 - 142 or 6 percent of supplies had initiated work on a plan.

What about hospitals and health services with drinking-water supplies that do not comply?
The review recommended that four hospitals or health services with drinking-water supplies that did not comply with the DWSNZ:2000 standard take immediate action to correct the problem and report to the DHB. This affects the Waiheke Health Trust and Canterbury District Health Board which were found to have E coli in water samples. It was also recommended that regular water samples be taken from the distribution zones that supply Te Puia Springs and Princess Margaret Hospital. Princess Margaret Hospital, which is owned by Canterbury DHB, now complies with the drinking water standards, whilst the Hillmorton Centre (formally Sunnyside Hospital and also owned by Canterbury DHB) is now connected to the town water supply.

What about school drinking water standards?
The safety of school drinking-water supplies is the responsibility of each school's Board of Trustees. Where a major upgrade is necessary, such as a new bore, the Ministry of Education will undertake the work under its capital works programme. Many schools have installed ultraviolet treatment in conjunction with cartridge filtration and the drinking-water standards will recognise UV treatment as a legitimate way of meeting protozoa compliance when the new DWSNZ:2005 standards come into force. Water suppliers considering installing UV treatment would be wise to assess the UV-treatment device to ensure it meets the new protozoa compliance criteria before installation.

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