New Zealand's water sector must do more to attract a pipeline of talent in order to meet safe drinking water and improved environmental standards, a new report says.

Water New Zealand estimates the sector needs an additional 6000 to 9000 skilled workers over the next 30 years, as the government moves to push its Three Waters reforms through the Parliament.

The report, which is a collaboration between Water New Zealand, Waihanga Ara Rau, the Department of Internal Affairs, Taumata Arowai, Connexis and industry leaders, details strategies for attracting, training and retaining a workforce that is "all but invisible to outsiders".

Water New Zealand chief executive Gillian Blythe says between $120 billion and $185 billion of investment over the next 30 years would require a broad range of extra staff, including operators, engineers and climate and data scientists.

"You can't have that amount of investment without increasing the number of people who are involved in designing, constructing, maintaining and operating that sort of infrastructure."

The report found the sector is inadequately prepared to build and operate new, technologically-advanced water infrastructure over the next decade, in the face of record-low unemployment, immigration restrictions and competition with construction and other industries.

Smaller providers often lack specialist skills, while a "lowest cost wins" approach to contracts has restricted the ability of some to train and employ apprentices, the report says.

"What generally happens is that the bigger businesses sweep up all the work because they've got the capacity to deliver. But then they sub out all the work - so they're taking massive amounts of margin out of the jobs, removing the opportunity to develop apprentices," an industry member says.

The report also highlights the challenge of gender diversity, with data showing just six per cent of water operators in Aotearoa are women.

"Male operators who we spoke with saw no reason why more women shouldn't be able to fill operator roles; however, there was a sense that women are fully accepted once they become 'one of the boys', the report says.

Jobs in the industry do not pay as well as many other sectors and employees often work long hours, the report found.

Water and wastewater treatment operators with up to two years' experience earn between $42,000 and $70,000, while team leaders or managers earn up to $130,000.

"In the face of the need to address a considerable infrastructure deficit, massive workforce competition and ongoing immigration restrictions, there is a significant need for growth in the sector. With many of the most skilled workers retiring in the next decade, succession planning is seen as one of the water industry's biggest challenges," the report says.

The report makes 14 recommendations, including creating better career pathways for school-leavers and progression for people already employed in the sector.

Under the Three Waters proposal, four large entities would manage drinking, waste and stormwater management instead of 67 councils.

-RNZ.