Drinking water

Description

Background, institutional arrangements and planning

In 2000, 82% of the total New Zealand population was serviced by 114 drinking water supplies. Each of these was a medium to large supply providing for more than 5,000 people.

The remaining 18% of the population is serviced by over 1,900 supplies that each provide for fewer than 5,000 people. Most of the supplies that failed to comply with the bacteriological requirement of the “Drinking-Water Standards for New Zealand 1995”[107] were from this group.[108] Many of these are poorer, dispersed rural communities that do not have ready access to laboratory facilities and have relatively high per capita costs for both treatment and monitoring compared to their larger urban counterparts.

To improve the public health management of drinking water supplies, the Ministry of Health developed management programmes emphasising planning techniques to promote a quality assurance approach. This is complemented by a monitoring programme used as a final quality control, which should also act as a feedback loop and provide a trigger for remedial action where this is necessary.

Up to 2007, legislation covering drinking water was included in the Health Act 1956 and largely related to local authorities. In 2007, the Health Act was amended to put all water supplies (public and private) on an equal basis in terms of water quality and quantity.

The Act also prescribes the management of water supply for safety, and requires local authorities to compile public health risk management plans as a means of ensuring issues that may compromise water quality are identified before they affect on the consumer.

Drinking water quality

Drinking water quality is monitored centrally by the Ministry of Health. The 2004 Ministry of Economic Development Stocktake[109] noted that complying with new drinking water standards (DWSNZ) proposed by the Ministry of Health would require many territorial authorities to upgrade their water supply infrastructure and management systems. This was an issue for many smaller rural councils, and a small number of metropolitan councils, where surface water sources were subject to minimal treatment.

Progress has been made in improving the quality of drinking water and wastewater infrastructure. In 2003, 68% of New Zealand's population received water that was known to comply with the bacteriological requirements of the drinking water standards. By 2008, this had increased to 80%. The graph that follows shows the increasing levels of drinking water supply registration since 1994, and improved levels of compliance with drinking water standards (with respect to bacteria).

The main reason for most of the remaining non-compliance with the drinking water standards in New Zealand relates to providing protection against protozoa (Giardia and Cryptosporidium). Chlorine does not disable protozoa, and the cost associated with the infrastructure required to disable them is high, as this requires either very fine filtering or treatment with ultraviolet light to disable it.

Figure 42: Trend in bacteriological compliance at the distribution zone

Source: Ministry of Health, 2010. This is a draft that, once finalised, will be published in the “Annual Review of Drinking-Water Quality in New Zealand 2008/9”

Despite the availability of a government subsidy,the substantial cost of new infrastructure to meet the increased legislative requirement to comply with the existing water quality standards remains a significant issue for many councils. Small rural-based councils typically have the greatest issue with compliance costs as their smaller water schemes (of which they may have a large number) may supply as few as ten properties.

Current New Zealand drinking water standards are based on World Health Organisation standards, are similar to Australian Guidelines and are less strict than European Union or United States Environmental Protection Authority standards. They were set in 2005 and amended in 2008. However, there is some debate as to whether the legislation should require rural communities to “take all practical steps” to comply. Consequently, the costs and benefits of complying with the standards are currently under review.

Assets

The estimated replacement cost of (territorial authority-managed) drinking water-related infrastructure in New Zealand is $11.4 billion.[110] Overall, metropolitan councils have fewer individual water schemes than provincial and rural councils. The greater length of reticulation associated with metropolitan councils reflects the greater intensity of development in these areas as a result of greater population growth. The following table indicates some of these differences.

Source: Department of Internal Affairs: Local Government Information Series 2009/19

The estimated capacity of the surveyed water supply systems totals 668 million cubic metres per annum. The capacity utilisation rates range from 22% to 92% and average 56%. This is the average utilisation over the year. However, there are seasonal peaks for both water supply and water demand.[111]

The production cost of drinking water is estimated to be similar for metropolitan and provincial councils (at around $1.20/m³) and lower for rural councils (at around $0.70/m³). The large range of values observed (up to $3.40/m³) reflects variation in the quality of the original water source, and geography.

Total annual operating expenditure on drinking water networks (including depreciation) is forecast to be $605 million per annum across all councils. Operating expenditure is forecast to grow by around 4.5% per annum over the next 10 years. Forecast capital expenditure over the next 10 years is estimated to be around $3,900 million.