The biggest problem that seems to occur with concrete swimming pools is the de-bonding of the plaster lining from the pool shell.
The reason for this defect is usually due to defective construction, including inadequate application of the pool lining.
The Australian Standard governing concrete swimming pools is AS 2783-1992: Use of reinforced concrete for small swimming pools. It sets out the basic requirements for the design and construction of a pool, and is worth a read if you’re in the construction business.
A useful tool for inspecting pools, particularly concrete pools, after the job is done is a “bathyscope”. It is a simple device that eliminates water surface reflection and allows underwater viewing. These can be found at boat shops, so you might also find it comes in handy out when you’re out fishing!