Following on from my previous question here concerning the ancient civilization I have called the Androy and their struggle to survive terrible drought conditions on their planet.
After years of struggling with having to dig deeper into an aquifer to extract water from underground the Androy encounter an even bigger problem. During routine deepening of the wells they encounter granite. They are at the bottom of the aquifer and within a few years will have to find water from some other source.
They are relatively close to the ocean. What techniques can they employ using ancient technology, to extract sufficient fresh water from the ocean to meet their needs? Can they extract as much from the sea than they could from the aquifer? Is it even practical?
The geography / geology of the coastline may be configured as you wish.