Cyclone Gabrielle: Gisborne Mayor Rehette Stoltz warns taps could 'run dry' in a couple of days

Gisborne's mayor is begging the residents to drastically cut their water usage, fearing the city might otherwise run out in "one or two days".

But with communications still down, it is not clear if the "urgent" message is getting through.

Asked when phone lines and cell connections would be back up, Rehette Stoltz told RNZ's Checkpoint on Thursday she had no idea.

"Today we can see that emotional impact it's having on our community, not being able to communicate with each other as well as whānau and friends across New Zealand and across the world.

"It is really having an emotional impact here, and we are crying - I know that Chorus are working 24/7 to fix the fibre, which is severed north and south of Gisborne. There is some temporary coverage here that some people are getting, the odd text, but it is really distressing."

Some temporary satellite connections were being set up, which would let people phone and text, but not use the internet, she said.

"That's better than nothing - people can then at least let their whānau know they are okay."

Twenty trucks arrived in the city on Thursday via State Highway 2, she said, bringing food, water and fuel. On Friday the navy's HMNZS Manawanui will arrive with more.

But for now, the potable water situation is "very tight", Stoltz said.

"We have one or two days. We started up our Waipawa treatment plant and that takes a few days to kick in. I think we started that up two or three days ago so there's some water there, but we need to use a quarter of what we usually use…

"Please conserve water urgently in Gisborne, otherwise our taps are going to run dry."

Progress with electricity is better, Stoltz saying "most" people would now be back on the grid, the improved weather making work easier for crews.

Prime Minister Chris Hipkins flew into Gisborne on Thursday morning, saying the sheer scale of destruction was "clear… even before we'd gotten off the plane". Stoltz greeted him at the airport, but he was not the only one.

"A lady came up to me and said, 'I have a 100-year-old mother in Napier and I cannot talk to her. I know she won't leave her house. I don't know how to reach her'. Those are the stories on the ground.

"Also, people who had floodwater through their houses - they want to ring insurance to get instructions on what they should do, and they cannot. So it is those practical things that are really becoming an issue after three days."

National Emergency Management Agency advice:

• Put safety first. Don't take any chances. Act quickly if you see rising water. Floods and flash floods can happen quickly. If you see rising water do not wait for official warnings. Head for higher ground and stay away from floodwater.
• Do not try to walk, play, swim, or drive in floodwater: even water just 15 centimetres deep can sweep you off your feet, and half a metre of water will carry away most vehicles.
• If you have evacuated, please stay where you are until you are given the all-clear to go home.
• If you don't need to evacuate, support those who do by staying home, staying off roads and staying safe.
• If you are not able to contact your whānau in the heavily affected areas go to Police 105 website and complete the inquiry form or phone 105 and remember to update if you reconnect through other means.
• Throw away food and drinking water that has come into contact with floodwater as it is often contaminated and can make you sick.
• If you are without power eat the food from your fridge first, then your freezer. Then eat the food in the cupboard or your emergency kit.
• People should stay up to date with the forecasts from MetService and continue to follow the advice of civil defence and emergency services.
• A National State of Emergency is in place for an initial period of seven days and applies to regions that have declared a local State of Emergency.