That's according to the UN agency for children or UNICEF which works with almost a million children across the region.
Pacific representative Sheldon Yett said there are many factors hampering progress on the issue including geography, natural disasters and the negative impacts of climate change.
"We are working actually to make sure that they can make the most out of the water that they have. To make sure that kids have access to good hygiene. To make sure that kids are teaching their parents and other community members what to do.
"You can't change geography and when you have very low water tables that is hard to get around. But it is really essential that we make the most of what we have there."
Photo World Bank Twitter