KEY POINTS:
A reduction in water demand could save Auckland households money, reduce the need for costly infrastructure upgrades and lessen the environmental impacts of our water use. The technologies to reduce water demand are proven, cost effective and available now.
As Auckland's population grows, it is no surprise demand for water - and the cost of managing it - is increasing.
Typically, most councils spend about a third of their annual operating budgets on delivering and managing the three waters - potable drinking water, stormwater, and wastewater. That amounts to billions of ratepayers' dollars each year.
In fast-growing urban areas like Auckland, the existing infrastructure simply can't cope with population growth and housing intensification. Pipes that once serviced one dwelling now service many. Wastewater and stormwater quantities are increasing while the reticulated pipes remain the same size.
The result is overflows and flooding during heavy downpours, and the need for expensive upgrades.
Recently announced increases in Auckland City water charges will ostensibly help to fund further infrastructure development to secure against the future population growth. One proposal is to pipe more water from the Waikato River; another is a new dam.
But here's the mystery. The Auckland region enjoys high rainfalls - at least seven-times more water falls as rain than is used by its residents. Does Auckland really need to increase its dependence on other regions - at great economic and environmental cost - to secure its future water supply?
A far cheaper, longer-term solution would be to help households to use less mains water. This would defer the costly expansion of the network for a good number of years and potentially save ratepayers millions.
Studies from New Zealand and Australia show that using a variety of water-management strategies, such as dual-flush toilets, low-flow showers and especially urban rainwater tanks, can significantly reduce demand on mains water supply.
Urban rainwater tanks don't just reduce demand for mains water. During heavy downpours, water is collected in the tanks, not spewed into stormwater drains. This means they help to limit flooding and the pressure on stormwater infrastructure.
Having a rainwater tank doesn't mean a cut from reticulated water services; it simply means using high-quality treated water for drinking, and using ample rainwater supplies for the garden, toilet-flushing and washing clothes.
Do our gardens, clothes and toilets need treated water, especially when it costs so much? Rainwater is free, and abundant.
Residential rainwater collection tanks are now mandatory in all new houses in Queensland, Victoria and parts of New South Wales, Australia. It's a necessary step. Water shortages are so severe the regions may not be viable in 50 years unless water demand is drastically reduced.
In Sydney, a per capita water reduction target of 35 per cent has been set for the next 25 years. In Melbourne, the target is 40 per cent. In contrast, the demand-management reduction figure set by Watercare Services for Auckland is only 5 per cent over the same time period.
Of course, Auckland's viability is not (yet) at risk as a result of water shortages. No, we will all just need to pay more - and more - for "quality" water as the city grows.
Sydney's 2005-06 Water Conservation and Recycling Implementation Report shows that fixing household leaks and fitting homes with water-efficient taps, showerheads and toilets, alone, has achieved savings of more than six billion litres of water a year.
The installation of 25,000 rainwater tanks is saving almost one billion litres a year, and 37,000 "Do-It-Yourself" water saving kits, distributed to residents, have reduced water demand by 250 million litres a year.
As a result of these and other initiatives, Sydney is using 40 billion litres less water annually.
In New Zealand, Beacon Pathway has been conducting research into cost-effective ways to reduce household mains water use, as part of a larger project investigating the sustainability of New Zealand's homes. The consortium has constructed two NOW Homes in Waitakere and Rotorua. Key areas of focus are on reducing mains water-demand and energy use.
The homes are being monitored, while occupied, to test the effectiveness of their design and construction.
Monitoring data from the first full year of occupancy in the Waitakere NOW Home shows that the household used 66 per cent less mains water compared to similar homes in the Auckland region - even with no change in the tenants' behaviours.
These savings are the result of simple water conservation measures: a rainwater collection tank providing approximately 47 per cent of the home's water needs, and low-flow taps and showerheads were installed. Dual-flush toilets account for only 7 per cent of total water use, compared to the usual 30 per cent.
Councils like Waitakere, the North Shore and Rodney have done work to encourage households to reduce their mains water demands. But their programmes are not as extensive as those in Australia, and lack the financial backing of central Government.
With a Government inquiry now likely to take place into Auckland's rising water costs, there is a real opportunity to explore not just the causes of the price hikes but also to protect against them well into the future.
There's an opportunity to discuss how to improve the sustainability of the nation's largest urban population's water supply by reducing dependence on centralised water reticulation services.
Quite simply, if there was less demand for reticulated water, there would be less need for costly infrastructure and associated costs funded at ratepayers' expense.
* Nick Collins is general manager of Beacon Pathway, a research consortium seeking ways to improve the sustainability of New Zealand homes.
