As well as assessing the impact of flaking paint on the walls of the pools, the review noted that there were unresolved problems with pool lifts and the position of heat generators.
It said: "Experience of this project suggests that the current estimates for completion should be treated with the utmost caution, as this project continues to be fraught with difficulty in determining not only correct and best solutions to such problems, but also in defining with any accuracy the expected costs of such actions."
The spa, designed by architect Grimshaw, was to be the first thermal public bath in the UK since 1978. However, a series of mechanical and cosmetic problems – together with disagreements between the council and the site contractor Mowlem – have delayed completion and increased costs to more than twice the original estimate.
Mowlem and Bath and North-East Somerset council emphasised that they continued to support the flagship project.
In the report, PriceWaterhouse Coopers said that the council's experience with the spa had triggered an internal review of the council's approach to major capital projects.