:(The leak was found to be coming from the fibreglass. The water did not travel from a different point on the spa, I saw the water droplet appear in the middle of the fibreglass. I have attached a photo.
I spoke with an engineer who explained what is likely happening.
When a hole is drilled in the shell, there can be a small chip on the edge. This chip can allow water to get between the fibreglass and the acrylic. In this Spa there was a gap in the Fibreglass the water could escape through. If the hole was not there then over time the water would build up, and where there are small gaps between the acrylic and fibreglass the spa will blister. Also where the acrylic is thin the spa is more likely to blister.
