Delegates from Canada, Lebanon, Turkey, Iran, the United States and Malaysia were due to gather for the Dushanbe International Water Forum to discuss problems as diverse as flooding, desertification and water-borne disease.
But it is unclear how much the conference will accomplish, since several of Tajikistan's neighbors who face grave water-related problems are not sending high-level government officials to the event.
The most notable among them are Uzbekistan and Kazakhstan, which share the Aral Sea -- once the world's fourth-largest lake that toxic waste has shrunk to a 400,000-square-kilometre wasteland that has become a symbol of the world's water problems.
The UN's new World Water Development Report estimates that some 2.2 million people around the world died due to water-related diseases last year.
Partly due to global warming (news - web sites), well over two billion people will be suffering from water scarcity by the middle of this century, the report warns.
But this deepening crisis "is essentially caused by the ways in which we mismanage water," the report reads. "The real tragedy is the effect it has on the everyday lives of poor people."
Tajikistan, which pushed to host the forum, faces water problems of a different sort. The mountainous country has enormous amounts of water, but much of it is not clean and the water supplies in the impoverished country are erratic.
The lack of access to treated drinking water means that water-related health problems like malaria are widespread in the former Soviet republic.
Water-related problems are also evident further along the banks of the Amu-Darya river, which flows from Tajikistan into Turkmenistan, where it crosses the Turkmen-Uzbek border before trickling -- in a good year -- into what remains of the Aral.
Tuberculosis and other diseases are on the rise among the people who scrape a living on the banks of the river's polluted shores, a leading non-government health organisation told AFP.
"The Central Asian nations still approach the issue purely as an engineering problem," the Kyrgyzstan office of the International Crisis Group wrote recently. "Each country has started to view the problem as a zero-sum game."
There are also worries that new demand for Central Asian water could come from neighbouring Afghanistan (news - web sites) as it rebuilds its war-ravaged economy.
"Rehabilitation work and investment are needed to help Afghanistan provide itself with enough water," Tajik foreign ministry spokesman Igor Sattarov said. "The drinking water problem is a global one."