Other possibilities might include creating combined teams specialising in wastewater modelling, standardised practices, shared billing, joint communication about water conservation and Dunedin making use of Christchurch laboratory facilities.
The Dunedin and Christchurch city councils have been looking into potential shared service arrangements, as it is hoped a partnership approach might produce cost savings and efficiency gains.
Several "promising areas" had been identified for detailed assessment, a report for the Dunedin City Council said.
However, Clutha District Mayor Bryan Cadogan said Dunedin could have also benefited by joining a local alliance.
There were benefits from Dunedin joining with Christchurch, as there would be from Dunedin being part of a southern conglomerate, he said.
"Where the advantages don’t lie as much is by doing it by themselves and we would have gained so much strength and so much cohesion to have a united Otago — and I think inevitably that day will come, because the financial benefits are too great," Mr Cadogan said.
"There are benefits to go to Christchurch, there are benefits to come to the southern region — there are benefits for us to all join together."
The biggest regret from his 27 years in politics was many neighbouring councils "did not see the wider helicopter picture" and they would all "be the poorer for it", he said.
Councils throughout the country have been evaluating how they might deliver water services — including by joining forces — amid rising costs and a pressing need for infrastructure upgrades.
The report for the Dunedin City Council about sharing some services with Christchurch said bulk procurement of smart meters, chemicals and pipes could reduce costs for the two councils.
Sharing expertise and peer-reviewing documents could reduce reliance on contractors and consultants.
The creation of standardised documentation for project management might streamline operations and joint development of water safety plans could avoid duplication, the report signalled.
The potential to establish a joint laboratory for testing of water quality could be evaluated, as well as the option of Dunedin possibly using Christchurch’s existing laboratory for tests.
Collaborative work for condition assessment of ageing infrastructure might also be on the horizon.
The two city councils have stopped short of deciding a combined entity should be set up between them.
They have instead been investigating various ways they might share services, after a working group was set up.
Feasibility assessments of opportunities identified as priorities are expected to be completed about August.
Implementation recommendations are expected to come before the Dunedin City Council for consideration in September.
Exploration of shared services between the two city councils has been happening at the same time as rural councils in Otago and Southland have proposed a combined entity.
The Clutha, Central Otago, Gore and Waitaki district councils are considering setting up a joint company to deliver water services and have been consulting their communities.
