Equipment that extracts fresh water from salt water is being delivered to the Tongan island of Niuatoputapu, where the water supply was damaged in last week's tsunami.
Nine people died on the island after a magnitude 8.0 quake triggered tsunamis in the Pacific on 29 September.
Red Cross emergency delegate Carl Burr says the few water springs on the island were damaged and the 1500 people on the island have been relying on water being shipped in.
He says the emergency equipment, consisting of a salt water pump, desalination unit and portable diesel generator, has the capacity to provide 3000 litres of clean drinking water a day.
It uses a filtration system to turn salt water into safe drinking water.
The device was designed last year and the Red Cross says it's the first time it has been used in the field.
Water and electricity supplies have been restored on American Samoa.
Electricity generation had been down down to a third of normal levels because the main power plant was damaged by the tsunami.
Two more devastated villages will get the chance to apply for assistance from the US government through the disaster recovery centre.
Scientists study tsunami effect in Samoa
A team of New Zealand engineers and scientists is studying the impact of the tsunami on buildings and infrastructure in Samoa.
The eight-person group from NIWA and GNS Science is joining other international survey teams.
Mission co-leader William Power, from GNS Science, says the aim is to help New Zealand and Samoa become better prepared for the threat of a tsunami.
Dr Power says a better understanding of the mechanics of tsunami wave movements in coastal settings will help improve the accuracy of computer models.
The group also plans to observe how different types of construction fared in the tsunami.