Damp in properties is a serious issue here in Spain!
It's due to insufficient damp proofing of the basement of an individual property, however if you act as a community on this under the 'building guarantee' then you will stand a better chance of resolving the issue.
You stated: "The water is coming from the rain falling on the area occupied by the garden surrounding the pool."
As there is insufficient drainage in the garden area, thus affecting the property in question, and it can be proved that this is the 'only' cause of this damp, then it may well be a community problem and the community will have to pay to sort it out.
Try and claim of the community insurance, as this may be covered by your policy.