The 10,000-plus delegates to the World Water Forum in Japan have a challenging week ahead.
By Ben Sutherland
BBC News Online in Kyoto
They must work out how to reach the UN target of halving the numbers of people without clean water by 2015.
They will have to tackle drought, floods, climate change, and the prospect of conflict over water.
More than two million people die annually from water-related diseases like cholera.
The forum, the third of its kind, runs from 16 to 23 March, and is sponsored by the World Bank, the UN, and many non-governmental groups. It is being held in three cities - Kyoto, Osaka and Shiga.
Two UN reports published earlier this month have highlighted the desperate situation some countries face as water resources begin to vanish at an alarming rate.
By 2020, the UN believes, the average water supply per person around the globe is likely to be one third smaller than it is now.
THE WATER STRUGGLE
Global water use has more than doubled since 1950
One person in six has no regular access to safe supplies
Contaminated water gives 200m people a year water-related diseases
Agriculture uses about 75% of global water consumption and industry 20%; much of it wasted
And they warn that it is a lack of both action and awareness that is exacerbating this crisis.
It is this, as much as anything else, that the World Water Forum is hoping to tackle.
Many of the conference sessions are precisely geared to generating ways of preventing water being wasted, be it through improved supplies or better irrigation methods.
But controversially, the conference will also examine how much water supplies could be improved with the involvement of the private sector.
Many NGOs have balked at that idea, insisting water is a right for all and should not be charged for.
Indeed, the Blue Planet Project - a coalition of environmentalists, human rights activists, and anti-poverty campaigners - was formed in direct reaction to the "Water Vision" proposed at the last World Water Forum.
This vision endorsed a for-profit view of water as a resource, they claim.
However, the success of water charging schemes in places like South Africa has encouraged both businesses and governments to consider a greater role for private sector involvement in the water supply.
The impact of dams is a key topic
But water privatisation is not the only controversial issue being raised here.
Dams, farming, and the damage caused to the environment by water projects will all be discussed.
Ultimately, however, the Forum is hoping to change people's lives for the better.
One of the targets of the UN Millennium Goals is to halve the proportion of people without access to safe drinking water by 2015.
Real progress towards this - and many other goals - could be made in Kyoto.
"The purpose of this conference is not to talk; it's for action," said William Cosgrove, vice president of the World Water Council, which is organizing the meeting.
"We've had enough talk and we've had enough general principles."