It's emerged that about a quarter of urban Marshallese lack access to water in their homes.
That's the preliminary finding of a European Union funded survey that has been looking at water access in the capital, Majuro.
The survey also shows the number of homes in Majuro have risen by 30 percent since 1991.
The government's water company is pumping rain and ground water to urban homes twice weekly, but only a third of people can afford it and households must additionally collect rainwater in private tanks.
But the planning office's director, Carl Hacker, says 23 % of those surveyed have no access to either form of water.
"There's no application for building permits. That makes it difficult to enforce building codes. Many of these people come from the outer islands, and people aren't gonna tell people you can't build a house. Most of these families, the watertanks, the piping, most families can't afford them."
Carl Hacker says with less rainfall forecast due to climate change, private watertanks will be especially important.