However, the two biggest urban centres in the southern region appear to be less keen to jump into the pool.
Councils in Otago and Southland are seeking to establish how they might best run water services amid burgeoning costs.
Consultancy Morrison Low said if there was not a change in approach, 76% of residential water users in the combined regions would have their water bills at least double between 2025 and 2034.
The remaining population could have their water bills increase by at least 75%.
Morrison Low concluded there were clear benefits for Otago and Southland to establish a water services entity covering both regions to provide Three Waters services.
The Gore District Council and Central Otago District Council announced last week recently they were looking to work together to deliver water in their communities.
Clutha District Mayor Bryan Cadogan said his council was expected to go in with others in the group when the matter was set to be discussed at a council meeting this week.
"It is our intention to [promote] collaboration efforts with anyone, not just limited to Otago-Southland.
"No matter how strong you are or think you are, you will be stronger if you get together."
Savings and resilience could be gained by councils supporting each other.
Fracturing into "sub-optimal wee groups" would impose unnecessary costs on to ratepayers, he said.
Waitaki District Mayor Gary Kircher said four councils had indicated a strong interest at a mayoral level in working together, and a fifth was interested.
"In addition, there are several others which may be interested."
Waitaki was one of the four councils interested but no decision had been made by the wider governance team.
Queenstown Lakes District Mayor Glyn Lewers said elected members would discuss water service options at a workshop in Queenstown next week.
He believed it would come down to finances.
"But long to medium term, our price path seems to fit within the middle ground of the forecast, if it’s a full grouping.
"There are some decisions to make ... I’m not closing it off, but I’m not committing either."
Gore District Mayor Ben Bell said rising costs had to be faced and the proposed collaboration with the Central Otago District Council was built on extensive financial modelling.
Central Otago District Mayor Tamah Alley said the two councils were leading the charge in tackling the complex issue of water services as a region.
A future-focused, sustainable model was needed, she said.
Southland District Mayor Rob Scott said councils were facing important decisions and they needed time to get them right.
Invercargill Mayor Nobby Clark said his council would discuss its preferred option tomorrow, but his personal view was Invercargill should continue as a stand-alone entity.
It had invested a lot in the past and was in a good position with its water infrastructure compared with other places.
"Why would I take the risk of not getting stuff done or getting additional costs because I want to get our ratepayers to help solve problems in other areas?
"I’m not here for that. I’m here as the mayor of Invercargill City."
At a meeting last week, the Dunedin City Council approved a shortlist for analysis and the options on it were continuing to deliver water in-house, setting up a council-controlled organisation for the city and being part of a multi-council entity.
A few city councillors indicated reluctance to pursue a regional council-controlled organisation.
By Grant Miller and staff reporters
