A moisture pump removes moisture from the terrain within its circular range, converting mud, marshes or shallow water into dry ground. The removal starts from the center and slowly expands outward. Moisture pumps do not affect deep nor moving water. The effect is permanent, you can safely dismantle them once the terrain is usable.
Its radius is 6.9 tiles, and takes 1 year (4 seasons) for it to fully expand.
Mud and marshes are converted into soil, while shallow water is converted to gravel.