About half of the marshlands area of Iraq has been restored to its 1970s condition, according to the United Nations Environment Programme (Unep).
Saddam's dams diverted waters away from the marshes
UN officials and Iraqi ministers told a seminar in Japan that drinking water supplies for the local population had improved, but remained a concern.
The area is believed by some to be the site of the Biblical "Garden of Eden".
Large areas were drained in the 1990s to punish the Marsh Arabs for rebelling against former leader Saddam Hussein.
By 2001, only one-tenth of the marshlands remained intact. Unep has been leading a project to restore the network of watercourses which provided inhabitants with water for drinking and farming, and supported the region's unique ecology.
"Working with Iraqi institutions and local communities, Unep is now providing safe drinking water to up to 22,000 people in six pilot communities by common distribution taps," said Dr Chizuru Aoki, Unep's Iraq project coordinator.
The agency has trained about 300 residents in marshland management.
The Iraq marshes lie between the Tigris and Euphrates rivers. They once covered an area twice the size of the Florida Everglades, and were famous for their biodiversity and cultural heritage.
A study in the 1970s said the marshlands were home to more than 80 species of birds, including about 90% of the world's population of the Basra reed warbler (Acrocephalus griseldis).
The wetlands also served as important fish spawning and nursery grounds, as well as acting as a natural filter for waste and other pollutants.
One effect of unrest is that demands for water are currently low
Tens of thousands of Marsh Arabs who lived in the area depended on the habitat for fishing and as grazing sites for their buffalo herds. But the marshes were devastated in the 1990s after Saddam Hussein's regime diverted water away from the region.
Following the US-led invasion of 2003, local citizens broke down the dams and dykes, re-flooding nearly 20% of the marshes. However, this unplanned flooding carried toxins from polluted ground into the wetlands.
Much remains to be done, indicated Iraq's Deputy Environment Minister Tuama Helou who was at the seminar in Japan.
"Clean drinking water is greatly needed in the marshlands," he said.
"Despite all the difficulties we face, including the security situation, we have to move forwards."
But it is unclear how far the restoration can go. Earlier this year a scientific team said demands for water will increase rapidly.
They predicted that as stability returned, more water would be abstracted for agriculture and hydro-electricity, by Iraq itself and by Turkey and Syria which lie upstream.