An accelerated resilience programme and the need to keep debt at a reasonable level have resulted in a 3% increase in the bulk water levy for the Porirua, Wellington, Lower Hutt and Upper Hutt city councils.

The increase was proposed in Greater Wellington's Long-Term Plan 2012-22, which was approved by Council yesterday. Greater Wellington manages water collection, treatment and supply to the four cities.

Cr Nigel Wilson, Chair of Greater Wellington's Social and Cultural Wellbeing Committee, says that Greater Wellington's Water Supply business has worked hard over the years to keep the levy as low as possible while providing an excellent service.

"For much of the past 15 years the levy has been held, and we've even lowered it three times. However, we're now in a new phase of water supply, which requires small annual increases in the levy," he says.

Cr Wilson says the increase is due to a couple of key factors.

"The importance of a resilient system has been reinforced by the Canterbury earthquakes and we now have an accelerated programme of improvements.

"We also know that we have to be ready to provide more water for the region's growing population. So by raising the levy in small steps to reduce existing debt, we'll avoid a big hike in the levy when the time comes to build a new water source."

Cr Wilson says that reduced water usage will help to keep the cost of water supply down.

"We'll continue to ask people to be careful with water and keep up the good work displayed last summer when we had the lowest water use in 15 years."