The Government must "govern and provide leadership" on water-sensitive urban design if we are to avoid worsening climate catastrophes", an international conference heard last week.
Speakers told Ecobuild that almost every level of leadership - from Government to businesses - are squandering chances to grasp the issue of good practice.
Landscape Institute president Sue Illman said the Government made encouraging sounds through white papers on water and natural environment. But drivers such as the Flood Water Management Act have not been fully implemented.
"The Government seems more interested in economic growth. This may explain why it hasn't been fully implemented," she added.
The private sector fails to look at whole-life costs and long-term benefits of water-sensitive urban design, fearing the high costs. But they fail to consider "what happens when it all goes wrong", said Illman.
Professionals needed high-profile champions and more interdisciplinary communication to foster non-confrontational, more collaborative working because "we can no longer practise in silos".
Melbourne's Cooperative Research Centre chief executive Tony Wong said: "Government needs to govern and provide leadership. It can't delegate its social responsibility to the private sector and needs to provide seed funding.
"One must not think about water management as a purely private-sector exercise. The way the private sector has broken up water management means they have their own corporate agendas and their solutions will be one dimensional.
"They will be dedicated to the shareholder rather than community benefit, which is not what city-building is about. We all have a role to play, but Government can't be silent on this issue - they must get the private sector to be socially responsible."
Aecom sustainability director Celeste Morgan said: "Our relationship with water should be about love. It identifies cities and helps them blossom into economic forces. Now it is more troubled. Waterways have been lost underground and the floods of 2007 cost £3.2m and killed 13 people."
GREEN DEAL GOVERNMENT DIVIDES OPINION
The Government split opinion on the Green Deal, when energy secretary Ed Davey told Ecobuild the initiative, which promotes housing sustainability, offers a huge opportunity to the construction industry.
In a water seminar, Landscape Institute president Sue Illman countered: "We are seeing business initiatives coming forward such as the Green Deal."
She added: "But this is a wasted idea because it is all about energy and it specifically precludes water."