Dialogue: Keep the best to drink - because we're worth it

JOEL CAYFORD* says the plan to mix treated water from the Waikato River into the main Auckland supply puts commercial needs ahead of public health.

The North Shore City Council adopted a "best water first" policy last week. The council accepts the proposed supply of drinking water from the Waikato pipeline, but only when consumer demand cannot be met by the purer raw waters stored in the Waitakere and Hunua mountain catchments.

To have effect, North Shore's recommendation will need to be supported by other Auckland councils, now collectively engaged in regional debate about the future structure of the water industry.

Councillors are grappling with the economic and environmental costs of the Waikato pipeline, the enormously expensive Mangere sewage treatment plant upgrade, increasing failures in sewage networks, a growing population, and who should pay for what.

Construction of the Waikato pipeline is scheduled to begin later this year. Under present proposals, whether the Waitakere and Hunua dams are full or not, treated water from the Waikato River will be injected directly into Greater Auckland's freshwater water reticulation system. After a host of uses, most water goes down the sewer to the Mangere wastewater treatment plant, though North Shore City's sewage is handled by its Rosedale wastewater treatment plant.

Because the region's population is rapidly approaching the capacity limit of the Mangere treatment plant of 900,000 people, planning is under way to build a further wastewater treatment plant in the northern part of the city to serve Kumeu, Riverhead and Hobsonville.

The more water fed into our drinking water network, the more wastewater comes out needing treatment. The full cost of the Waikato pipeline is not just its $155 million price tag. It includes another treatment plant and a discharge to dispose of the extra wastewater.

Existing ratepayers will pay for these new project costs through increased user charges. This is an unfair allocation of costs. A regional development levy should fund capital investment to meet the water demands of new residents.

The Mangere treatment plant upgrade is required to meet tighter environmental standards and will cost ratepayers $460 million. Rates have gone up to cover the costs this project is passing down the chain, but these increases are small compared with the likely cost of sewer infrastructure repairs across Greater Auckland.

The North Shore City Council's investigations show the bacteria affecting beachwater quality after heavy rain are mostly from sewage and contaminated stormwater overflows. Less than 1 per cent of beach water contamination comes from the sewage treatment plant outfall. So because the major source of pollution from North Shore City's sewerage system is poorly maintained sewer pipes, the bulk of sewerage infrastructure expenditure is targeted at fixing pipes - not the treatment plant.

Public information shows that pipes and manholes in Auckland, Waitakere and Manukau sewer networks routinely discharge raw sewage. This suggests that the $460 million upgrade of the Mangere treatment plant deals with the tip of a contamination iceberg. Their sewer network rehabilitation price tag will be more than $1 billion.

After its upgrade, Mangere will produce an effluent of higher quality than the wastewater plant in San Diego, where treated effluent is reticulated and used for a huge variety of non-potable purposes - saving precious drinking-quality water. No concrete plans yet exist for this practice in Auckland. The North Shore City Council, however, uses treated wastewater on the Pupuke Golf Course, and has plans to irrigate other green spaces.

The Waikato pipeline will also produce highly treated effluent. Treated sewage from hundreds of thousands of people, and untreated sewage from hundreds of thousands of farm animals flows into the Waikato River.

Both the Ministry for Environment and the Parliamentary Commissioner for the Environment have expressed concerns about the health of the river downstream from Hamilton.

The Waitakere City Council has argued that we should fix the water leaks in our water pipes before building the Waikato pipeline. I have suggested incremental, less capital intensive projects, such as the Lower Mangatawhiri Dam or Wairoa River.

Whatever augmentation is built, water management wisdom around the world points to the use of the highest quality raw water source for the highest need - human consumption.

If public health was the priority in providing fresh water, treated Waikato River water would not be provided ahead of, or mixed with, treated water from existing dam catchments.

But when commercial needs dominate - as they do in Watercare, a local authority trading enterprise - there will be an overwhelming need to extract revenue from the Waikato pipeline and pay off debt. So lake water will be spilled and raw water that is more expensive to treat and requires lots of electricity to get over the Bombay Hills will be supplied instead.

It does not have to be this way. And nor should it. The water demands of Greater Auckland has grown and become more sophisticated. The people deserve water management and integrated water investment decisions which balance health, security, social, economic, environmental and commercial priorities.

True costs must be assessed and properly allocated. And we deserve the best water possible.

* Joel Cayford is the North Shore City Council representative on the Watercare Shareholders Representative Group.