Heavy rain

They said tap water in much of the Cook Islands comes straight from the mountains and with recent heavy rainfall it was possible it could be contaminated.

Health protection officer Charlie Ave said they have a simple message for friends visiting from across the Pacific.

"When they come here they boil the water and let it cool down before drinking, or otherwise we have UV treated water stations around the islands where they can get their water from, or buy it from the shop," said Charlie Ave.

RNZ reports a tropical low is about 600 kilometres west-southwest of Rennell, and is moving southeast.

A heavy rain warning is in force for all provinces.

The meteorological service says people in low lying areas by rivers and streams should prepare for possible flooding and landslides.

Disaster officials say there are no confirmed fatalities after landslides in the capital, Honiara.

Photo by Solomon Islands Met  

Ignacio has grown to a Category 4 storm, with sustained winds of up to 140 mph. Forecasters at the Central Pacific Hurricane Center said conditions are right for it to continue strengthening Saturday, but upper-level winds will weaken the storm in the following days.