Clutha District Council identified a replacement pool and library/service centre complex as a priority for the South Otago town during annual plan consultation in 2019.
A concept design publicised by the council then was priced at $5.8 million.
Since then, a community trust formed to oversee the project conducted "significant" behind-the-scenes consultation work with key stakeholders, who have expressed a desire to build an upgraded facility.
Revised estimates for two scaled-up options will be presented to the wider community for final consultation next month.
The two options will allow for a 2713sq m, six-lane pool and combined library/service centre complex, at $10 million-$11 million; or a 3360sq m, eight-lane pool complex, at $14 million-$17 million.
The facility will be built on the library/service centre site in Union St.
Pool committee member Dale Wyber said cost-increase drivers included global inflation, but mostly stemmed from a desire for an enhanced facility.
"That initial figure was always very loose, for what was a basic concept design.
"Since that time, the committee has done significant work behind the scenes consulting schools and other key groups locally, and refined down their wish list to a concept that’s much more suitable for what the community wants and needs for the future, while remaining feasible, cost-wise."
A recent council report said the pool committee would expect to raise $2 million of the total, while an unconfirmed $1.9 million would come from governmental Three Waters "better off" grant funding, and the remainder via general and targeted rates.
Fellow committee member Kim Schiller said the new facility would be an asset to the district at large.
"This isn’t just for Milton, but for Bruce district as a whole, and as a future-proofed facility for Clutha.
"The initial plan was for a small facility that would have been ‘just OK’. Our community wants and deserves more than that, so we’ve worked to give them that option, including what we hope will be a year-round pool facility and an innovative, interactive library space."
Mrs Schiller said the project, which will run in parallel with a further $5.5 million of imminent civic improvements for Milton, would be "transformative" for the area.
"Seeing the community’s desires taking shape will be very exciting. The real work begins now, and we hope the community will get behind us to make this once-in-a-lifetime opportunity a reality."
Consultation on the revised options will begin on June 7.
