Four days after kings tides hit the low-lying Pacific nation of Kiribati authorities say one of their biggest challenges is getting clean water to affected communities.

The king tides caused widespread inundation on at least five islands and hundreds of people are living in temporary accommodation.

Michael Foon, the disaster risk manager in the president's office, says ground water supplies have been contaminated on at least one island, South Tarawa, and crops have been destroyed.

"We know that ground water in that area has been severely contaminated," he said.

"We know that bread fruit trees and papaya, taro have been affected."

Mr Foon says authorities are still trying to assess the full extent of the damage and several islands are yet to send reports.

Flooding caused by king tides at Ambo village, South Tarawa island, Kiribati. ( Supplied: Office of President, Kiribati )

He says there have been reports of damage to coastal infrastructure.

"We know there has been damage to residences on the outer islands," he said.

"On South Tarawa we know that there is a lot of damage to coastal infrastructure like sea walls and causeways."

Mr Foon says it will be some time before the worst affected areas recover from the inundation.

"We know that the areas where ground water has been affected there will be long term consequences of that," he said.

"It will take weeks or months before the water system in that area is fully recovered."