Southland's water carriers are having to prioritise jobs to ensure those with the greatest need get water first.

Cleanways owner Lloyd Phillips said they were snowed under despite having all six of his company's water tankers currently on the road.

"It’s tough when you haven’t got any water in your tank."

"We are trying our hardest to service the most needy."

However Phillips emphasized the importance to maintaining good communications with customers.

"[We] make sure we get to those that are right out of water, and those that have got a wee bit left in their tank .. we deliver to them on the days that they are out," he said.

He said the duration of the dry period had made it tougher, with many that got water early now requiring second loads.

Phillips estimated half his customers had never received water from him before.

Southland Water Carriers is also very busy and having to prioritise customers, according to part-owner Nicole McLeod.

"We’ve done more in the last month than what we did in half a year. It’s huge," McLeod said.

"We’re working 7 days a week and bringing in extra staff. It’s busy."

Scully Transport owner Brent Scully estimated demand for water had doubled.

He said there was a lot of people getting water who hadn't needed it before.