RimWorld Moisture Pump: Radius, Time, and What Terrain It Actually Dries (1.6)
RimWorld 1.6 · Core
Fast answer: the moisture pump slowly dries wet terrain that can convert to dry ground — marsh, mud, marshy soil, soft sand, and shallow water. Research moisture pump, build it from architect → misc, and wire 150 W. Full reach is radius 6.9 over 60 days. It cannot dry deep water, rivers, or ice. Once placed, you cannot uninstall it — there is no off switch either.
At a glance
| Stat | Value |
|---|---|
| Cost | steel ×75 + component ×4 |
| Power draw | 150 W |
| Construction skill | 6 |
| Build work | 1500 |
| Hit points | 50 |
| Architect tab | Misc |
| Radius | 6.9 |
| Days to full radius | 60 |
| Rotatable | No |
| Uninstall / power switch | Cannot uninstall or reinstall; no power switch |
In-game description: “Very slowly equalizes moisture in nearby terrain, converting marshes or shallow water into dry ground, and soft sand into normal sand. Does not affect deep water.”
Do this in-game: research and build
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Open research F6 and finish moisture pump (1200 points, Industrial). Prerequisite: microelectronics basics.
research → moisture pump -
Place the building: architect → misc → moisture pump (75 steel, 4 components; Construction 6; build work 1500).
architect Tab → misc →moisture pump
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Connect power (150 W continuous). There is no flick switch on the pump — to stop power draw you must disconnect the wire or deconstruct the building.
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Wait. Drying spreads outward to radius 6.9 over 60 in-game days. Plan placement carefully: the pump cannot be uninstalled once built.
Permanent placement. You cannot pack it up and move it like a deep drill. There is no power switch — it runs whenever it has power.
What each wet terrain becomes
Some terrain types dry into another tile type; others are unaffected. If a terrain has no dry conversion, the pump does nothing to that tile.
| Terrain | Becomes | Notes |
|---|---|---|
| Marshy soil | soil | pathCost 14, fertility 1.0 |
| Mud | soil | pathCost 14, fertility 0 |
| Marsh | soil | Directly to soil, not marshy soil |
| Soft sand | sand | Matches the building description |
| Shallow water | gravel | Not soil — low fertility |
| Shallow ocean water | gravel | Saltwater; cannot freeze |
| Shallow moving water (river) | — none — | River tiles; cannot be dried |
| Chest-deep moving water | — none — | River; cannot be dried |
| Deep water | — none — | Permanent water; cannot be terraformed |
| Deep ocean water | — none — | Same as deep water |
| Ice | — none — | Cannot be terraformed |
Shallow water becomes gravel, not soil or stony soil. Rivers and deep water are untouched. Ice cannot be dried.
Practical tips
- Swamp maps: pumps turn marsh/mud into tillable soil — the main reason to build them.
- Shorelines: shallow water dries to gravel (70% fertility). Useful for reclaiming beach tiles, not for rich farms.
- Deserts: soft sand becomes normal sand so you can build on it.
- Multiple pumps: overlapping radii dry separate patches in parallel. Each pump is a permanent 150 W commitment.
- Bridge trick: you can build a pump on a wooden bridge over marsh or shallow water to start drying from the middle of a wet patch.
- Do not expect river or ocean draining: moving water and deep water cannot be dried. The building description explicitly excludes deep water.
How long does drying take?
The pump reaches its full radius of 6.9 cells over 60 in-game days. Tiles closer to the pump dry sooner; the estimate below scales with that 60-day / 6.9-radius timing.