A lack of clean drinking water in Indonesia's quake zone remains a top priority for aid agencies racing to provide assistance to hundreds of thousands of survivors, the UN Children's Fund said.
"The key thing from our perspective remains making sure people get clean water," UNICEF spokesman John Budd said.
"If we don't get clean water to them, that will create a health issue. These people are physically vulnerable they are weakened by injury and suffering from psychological trauma. On top of that, they're homeless."
Aid continued flowing into the quake zone on Indonesia's main island of Java on Wednesday, with relief efforts facilitated by cool, dry weather overnight.
Budd said 45 trucks were ferrying water into the area 30 operating in the hard-hit Bantul district south of Yogyakarta and 15 others working in Klaten district east of the city.
The vast majority of the nearly 5,700 people who died in Saturday's 6.3-magnitude earthquake lived in the two districts.
The trucks can bring a total of 720,000 liters (190 US gallons) a day into the area, Budd said.
Nine of the 12 water treatment plants in Bantul were rendered inoperable by the quake, but Budd said some of them should be back up and running by later Wednesday. In Klaten, all seven treatment plants were intact.
"What we're worried about is sewage seeping into the aquifers near the surface. Then we'll have contamination issues," the UNICEF spokesman said.