Monthly billing under a strict user-pays policy has driven Aucklanders to cut their water use to the same level as during the severe 1994 drought, when official restrictions meant washing water was collected in buckets and used to flush toilets and to water gardens.
Paying for metered water coming in through the tap as well as what goes down the drain has made Aucklanders the country's most frugal consumers of municipal water supply.
Figures from Watercare Services, which supplies 93 per cent of the region's population, show Auckland's consumption is 271 litres a person per day compared with 425 litres during the 1980s. In 2004, the daily use was 298 litres a person and Watercare says it is on target for reducing this by 15 per cent to 253 litres a person per day by 2025.
It credits the steady decline to universal metering and a user-pays system of charging.
The introduction of monthly billing in July 2012 also prompted people to report leaks. Watercare says it also puts a conservation message in its bills to its 430,000 customers and on its website.
Water conservation campaigner Joel Cayford said it was a "strong economic incentive" to save when you had to pay twice for the same water.
Waste water disposal was charged at 78.5 per cent of the volume of water coming into the property. Tap water costs $1.343 per 1000 litres.
However, Dr Cayford said it was disappointing that Watercare was not as active as electricity retailers in encouraging conservation. It should offer discounted kitsets to divert grey water from household washing into garden use.
He believes that conservation initiatives would benefit the existing network and delay the need for Watercare's plan to seek resource consent to double its take of raw water from the Waikato River near Tuakau.
Watercare says it has enough to meet drought requirements for the present. But if Auckland's population grows as predicted, it will need to increase supply capacity by a further 200,000cu m a day (1cu m equals 1000 litres).
Pumping it north from the river is the preferred way of satisfying theneed.
Up to 30 per cent now comes from the riverside treatment plant though Watercare says water from its nine dams is used ahead of the river source.
Daily use per person
271 litres Auckland
380 Lower Hutt