Mud

Mud is a naturally occurring element in Oxygen Not Included that functions as a convertible raw material rather than a finished resource. It appears in the base game and in the Spaced Out content as a harvestable and producible substance used primarily as a source of Dirt and Water when processed. Mud is produced biologically and can also be collected on certain Space POIs.

Mud is processed most commonly with the Sludge Press, which decomposes Mud into Dirt and Water at a fixed conversion: 150 kg Mud → 60 kg Dirt + 90 kg Water. Heating Mud instead converts it into Dirt and Steam in the same mass ratio; this conversion generates heat overall because both Steam and Dirt have higher specific heat capacities than Mud. When Mud is converted by heat the Dirt portion is always produced as debris, even if the original Mud existed as a tile rather than debris.

Mud production and acquisition:

• Grubgrub creatures produce Mud by consuming Sulfur or Sucrose. Farming Grubgrubs is a renewable in-base method to generate Mud.
• Mud is available as a POI harvest on rocket missions in the Spaced Out expansion. Swampy Ore Fields yield Mud at rates between 108 kg and 324 kg per cycle, making these POIs a reliable external source when onboard resources (like Dirt near a Printing Pod) are scarce.
• Using the Sludge Press near the Printing Pod is often useful because printed starting areas (or rocket landing areas) can lack Dirt; converting Mud to Dirt covers that shortage.

Practical notes and interactions:

• Converting Mud by heating creates Steam in addition to Dirt; plan for steam management and condensation to recover water or to avoid pressure/temperature problems.
• The Dirt output from Mud conversion always appears as debris, so plan storage or conveyance systems that handle debris rather than tile placements if you intend to transport raw Dirt before using it.
• Sludge Press processing yields both a solid (Dirt) and a liquid (Water), so integrate plumbing and conveyors accordingly to capture both outputs efficiently.
• Because Mud can be produced on a renewable basis from Grubgrubs and harvested in space, it serves as a mid-tier substitute when Dirt supplies are constrained but should be processed with facility readiness for heat and multiphase outputs.

Mud is therefore a flexible intermediate resource: easiest to use when you have a Sludge Press or controlled heating, useful for topping up Dirt and Water supplies, and obtainable both in-system via creatures and off-world via mission harvests.