(CNN) -- A water shortage in the Bangladeshi capital Dhaka is so acute that troops have been called in to guard water pumps in parts of the city.
The city of more than 13 million people experiences a water shortfall every year during the peak dry season in April and May, but this year it is particularly bad, the United Nations said.
Soldiers were called in to help coordinate water distribution after protests by residents, angry at the worsening situation, said the U.N.'s Integrated Regional Information Networks (IRIN).
Two factors have exacerbated the shortage this year: Lack of rain has caused groundwater levels to drop. And regular power outages have made it difficult for officials to pump what is needed.
The city's water supply authority has 545 water pumps but only 293 generators, IRIN said. In addition, the city needs 2.2 billion liters of water a day, but can only produce 1.9 billion.
As a result, people are relying on surface water that is often contaminated. And hospitals throughout the city are experiencing a spike in water-borne diseases.
A World Health Organization assessment of sanitation and drinking water this year found that more than 30 million people in the south Asian country do not have access to safe drinking water.
Over the last decade, ground water levels have been declining by up to three meters (9 feet) a year, the U.N. said. At the current rate of urbanization, access to clean potable water could get worse, it said.