Storms which drenched Queen's Birthday holidaymakers and caused floods in parts of the country have barely dented Auckland's water shortage.

Watercare says Auckland's nine active water storage dams have filled only marginally, from 42.54 per cent of capacity last Monday to 43.59 per cent today.

Their normal level at this time of year, before the main winter rainfall from July to September, is 76.65 per cent.

More rain is forecast this week, but the medium-term MetService forecast is still for less rain than usual in all areas in the second and third weeks of June, and less than usual even in the coming week in the crucial Hunua catchment which supplies 60 per cent of Auckland's water.

Watercare chief executive Raveen Jaduram said the lake levels might rise by a further 1 per cent over the next few days as water seeps in from the surrounding catchments, but the weekend rain was "not a drought-breaker".

"We appreciate every drop we can get, because we didn't get enough over the last few months," he said.

Rainfall at Auckland Airport dropped to below 25 per cent of normal in January and February and has now been below normal for each of the past eight months to the end of May.

MetService said May's rainfall of 101.8mm was 83 per cent of the historical average for May, the highest percentage since last September. But the average over the full eight-month period is still only 54 per cent of normal.

On the other hand, the latest Watercare data shows that Aucklanders have responded to calls to save water, using an average of only 405 million litres a day in the week to May 31.

Raveen Jaduram: "I am very pleased that the people are doing good stuff." (Photo / File)

Jaduram said water use started May at 440m litres a day and the target for May was to reduce that to 420m litres.

"I am very pleased that the people are doing good stuff," he said.

"Mums and Dads, you and me, are doing our bit, and large businesses are doing their bit, so everyone is pulling together," he said.

He said a survey last week found that 75 per cent of Aucklanders were aware of the water shortage and knew what they had to do, such as taking shorter showers.

"Most of them were saying that they were actually responding," he said.

But he said the water restrictions would need to continue to ensure that there was enough water for next summer.