Zaha Hadid's distinctive wave-shaped roof has been reduced to a third of its original size

Revised designs for the aquatic centre at the London 2012 Olympics will mean a less ambitious roof design, it was revealed today.

The scaled-down centre, designs for which were revealed by architect Zaha Hadid and the Olympic Delivery Authority, will mean the roof would be a third smaller than the original plans, which were rejected by culture minister Tessa Jowell for being too expensive.

The roof has been reduced down to 14,000m2 from the original size of 35,000m2.

David Higgins, the ODA’s chief executive, refused to be drawn on how much the new centre will cost. In London’s original bid for the 2012 Games the aquatic centre was priced at £75m.

Higgins said that one advantage of the smaller roof, which will be made of steel, reducing the risk of going over-budget and time.

The design includes a wave-shaped roof symbolising the flow of water. It will include two 50-metre pools for training and competition and a diving pool and will have a 20,000 capacity.

Construction is expected to start in mid-2008 and completion is due by the summer of 2011 in time for testing.

After 2012 the centre will be converted into a 2500-capacity venue for national and international events as well as use by the local community. Sebastian Coe, chairman of the London 2012 Organising Committee, said that it was not yet clear who would operate the centre after the Olympics. “That is still one of the issue we are dealing with,” he said.

Higgins said: “The revised design, while just as visionary and exciting, is smaller than the original, reflecting the new constraints of the site. These are world-class designs and the aquatics centre will be a magnificent Gateway to the Games.”