More than 1 million people have been affected by the flooding, triggered by unusually heavy monsoon rains in the last two weeks.
"Global weather patterns are changing, we should be prepared for extreme changes," said Gunavi Samarasinghe, director of Sri Lanka's Meteorological Department, Inter Press Service News reports.
Although the country has been hit by severe flash floods three times since May, marooning a total of 2.2 million people, the U.N. Global Disaster Alert and Coordination System has categorized the latest flooding as an extreme event that wouldn't be likely to recur in 100 years.
Samarasinghe said the latest flooding has been the most destructive, second only to the 2004 Asian tsunami. Estimates have put the cost of the damage at $500 million.
Amid the massive flooding, lack of drinking water is a growing problem for the Vanni region in northern Sri Lanka, reports IRIN, the news service of the U.N. Office for the Coordination of Humanitarian Affairs. Decades of civil war have left the water infrastructure in near total disrepair.
"You have to begin everything anew," said Samantha Wijesundera, water and sanitation expert at the World Bank's Sri Lanka office, noting that the last wave of fighting between government forces and Liberation Tigers of Tamil Eelam separatist rebels from mid-2007 until May 2009 damaged or destroyed nearly all the water facilities.
Piping water to the former conflict zone, which is experiencing the return of tens of thousands of civilians, is a top priority for the government, experts say.
Just three out of 10 people, on average, have access to piped water in the five districts of the Vanni region, which relies mostly on streams, unprotected wells and closed hand pump-operated wells for drinking water.
"There are areas of concern over the quality and safety of currently available water sources and resources," said Abdulai KaiKai, chief of water, sanitation and hygiene at UNICEF in Sri Lanka.
So far $1.8 million worth of projects were under way in Jaffna and parts of the Kilinochchi districts, both in Vanni. The projects are expected to provide piped water to more than 350,000 people out of an estimated population of 850,000, a government official told IRIN, with the first pipes slated to be operational by early 2015.
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