Slowly removes moisture from terrain in an expanding circle. The circle expands continuously (approx. 8.7 days per tile radius), reaching a full radius of 6.9 tiles after a year.
Mud, marsh, and marshy soil are converted to soil. Soft sand is converted to sand. Shallow water and shallow ocean water are converted to stony soil (or ice on sea ice biomes).
All other terrain types are unaffected by moisture pumps.
It requires Moisture pump research to be built.