Guide/Water Production (2024)

Water is one of the most valuable resources in Oxygen Not Included. This guide will explain how to make your own water when you run out.

Water-based Resources and Conversion

• Water is the most generally useful, and rarest in the general environment. It is usually found in the starting biome near the Printing Pod, and occasionally in small pockets or Ruins. Most water will have to be produced from other water-based resources.
• Polluted Water is produced by a variety of life support and industrial processes, as well as being found in a variety of biomes. In addition to water production, various agricultural processes use polluted water directly, making maintaining an additional stockpile can be useful - though care should be taken as in low-pressure environments it evaporates into Polluted Oxygen. It has the highest boiling point among water-based resources, and thus is often used as a coolant.
• Salt Water is found in some biomes, and cannot be produced by duplicants - the only renewable sources are space missions and the Salt Water Geyser. It can be used to grow domestic Waterweed, converted into water and salt by boiling or a Desalinator, or cooled to produce ice and brine.
• Brine is found in cooler salt biomes, and can be produced by cooling salt water. It has the lowest freezing point of the water-based resources, so it can see some use as a coolant, but its lower specific heat means polluted water is generally more useful unless the low-temperature performance is required. Other than as coolant, its only use is to be converted into salt and water.
• Ice, Snow, Crushed Ice, Polluted Ice, and Brine Ice all melt to their corresponding water type; an Ice-E Fan can be used to accelerate this process, transferring 32kDTU/s (roughly equivalent to the output 1.8 Space Heaters) when operated in a warm environment.
• Steam is the result of boiling any water-based resource. Water converts 100% of its mass to steam, polluted water converts 99%, salt water converts 93%, and brine converts 70% - for brine and salt water this is the same ratio as using a Desalinator, but some water is lost when boiling polluted water compared to a Water Sieve. Steam will always condense to pure water, either by lowering its temperature or by feeding higher-temperature steam (above 125 °C) into a Steam Turbine, which will process 2kg/s of steam into 95 °C water as well as generate power.

Geyser Taming

Seven Geyser variants produce water or related resources on a regular schedule. In roughly increasing order of complexity:

• A Water Geyser produces clean water at 95 °C. A Gold Amalgam Liquid Pump (or possibly two, to avoid overpressurising) suffices to add it to your water system immediately.
• A Salt Water Geyser produces salt water at 95 °C, which can be passed through a desalinator and into the network. (It can also be boiled, which is more energy-intensive but does not require duplicant maintenance.)
  • This is the only renewable source of salt water without rocketry, so it should prioritise any Waterweed farms before a Desalinator.
• A Polluted Water Vent produces polluted water at 30 °C, infected by Food Poisoning germs. Germs are not destroyed by a Water Sieve, so duplicants can still be infected if they consume the water or food grown from it. See Guide/Disinfect Germs for an effective way to eliminate the germs before use.
• A Cool Salt Slush Vent produces brine at -10 °C. This is too cold to run directly through a Desalinator without breaking the pipe, so it should be run through a heat exchanger or used to cool other parts of the colony before being moved into the water system.
• A Cool Slush Vent produces polluted water at -10 °C. Many of the isssues of the salt slush geyser apply here, but polluted water has a higher specific heat than brine - making it a more effective coolant but needing more heat to reach safe temperatures.
• A Cool Steam Vent produces steam at 110 °C. As this is too low-temperature for a Steam Turbine, it needs to either be heated (to 125 °C for turbine input) or cooled (to its condensation point for a liquid pump) to produce usable water. Cooling the steam requires slightly less heat transfer than heating it (-52,864 DTU/kg vs 62,685 DTU/kg), but heating the steam allows the system to serve as a heat sink for other machines.
• A Steam Vent produces steam at 500 °C. The simplest way to extract water is to directly feed this to a turbine (a Thermo Aquatuner will still be needed to prevent it from overheating - due to the high temperatures, it must be placed outside the geyser room unless Thermium is used). More complex builds will cool the steam to 200 °C using heat exchangers which feed additional turbines, dramatically improving Power production.

Lavatory Loop

Things you'll need: Lavatory, Water Sieve, Filtration Medium

Each use of a Lavatory will produce 11.7 kg of Polluted Water from 5 kg of Water, which essentially means each Duplicant will produce a net gain of 6.7 kg/cycle (or 13.4 kg/cycle with the Small Bladder trait) if lavatory output is run through a Water Sieve.

This water will contain food poisoning germs, which makes them unsuitable for direct consumption; see Guide/Disinfect Germs for eliminating germs before introducing lavatory water to the primary water supply. In order to stop lavatories from backing up with produced polluted water, it may be desirable to connect an overflow bridge to a Thimble Reed farm.

Pufts (Polluted Oxygen input)

Things you'll need: Puft, Algae Distiller, Polluted Oxygen source.

The puft will inhale polluted oxygen and defecate slime. The slime can be placed in an algae distiller and is turned into algae and polluted water, which can be used or filtered as needed.

Petroleum and Natural Gas Generators

Things you'll need: Petroleum Generator or Natural Gas Generator; Crude Oil and Oil Refinery or Ethanol or Natural Gas

Burning hydrocarbon fuels (Petroleum, Ethanol, and Natural Gas) will produce polluted water in the surrounding environment at the temperature of the generator.

Note that renewable sources of these materials (Oil Well+Oil Refinery or Arbor Trees) will on their own result in a net loss of water even after fuel is burned. When environmental sources of crude oil and ethanol have been exhausted, additional systems are needed to obtain water renewably - see the zero-inputs setups below.

Arbor Tree Pip Farming (zero-inputs)

Things you'll need: Pip, Arbor Tree, Ethanol Distiller, Petroleum Generator

Wild-growth Arbor Trees harvested by duplicants produce ~83.3kg/cycle of Lumber at no resource cost. An Ethanol Distiller converts 50% of lumber mass to ethanol, and a Petroleum Generator converts 67.5% ethanol mass to polluted water - each wild tree thus essentially produces ~26kg/cycle of germ-free polluted water at no cost, in addition to a small amount of power, Carbon Dioxide, and Polluted Dirt.

Pips can be used to plant wild trees at any location. Deconstructing a Manual Airlock which is surrounded by tiles will produce natural tiles from the door's ore, which are suitable for pip planting.

Petroleum Boiling (zero-inputs)

Things you'll need: High-temperature heat source (Volcano, Minor Volcano, Steam Vent); Oil Well; large amounts of Steel

Heating Crude Oil to its turning point will convert 100% of its mass into Petroleum, compared to only 50% conversion from an Oil Refinery - this is enough to make Petroleum Generators and Oil Wells water-positive. See Guide/Petroleum Boiler for details; once constructed, this will produce a net ~3.75kg/s of polluted water and ~10kW of power without duplicant labour or external input.

A Thermium Thermo Aquatuner can also be used as a heat source, but with access to space materials it's more effective to produce Sour Gas (see below).

Pufts and Arbor Trees (Spaced Out! zero-inputs)

Things you'll need: Puft, Algae Distiller, Arbor Tree, Ethanol Distiller, Petroleum Generator, Sublimation Station, Compost

The Sublimation Station's rapid conversion of Polluted Dirt allows for a combination of the puft cycle with ethanol generators which is completely resource-positive, requiring no external inputs other than duplicant labour.

A stable of six pufts will consume 500g/s of polluted oxygen (with a further 50g/s from a single puft prince to keep it stocked with eggs); this will in turn produce 480g/s of slime, which distills to 320g/s of polluted water - or 192 kg/cycle.

Eight Arbor Trees consume 560kg/cycle of polluted water and 80kg/cycle of dirt to produce 83.(3) kg/cycle of harvested Lumber. This is enough to run (slightly more than) four ethanol distillers for 2kg/s of ethanol and 1.3kg/s of polluted dirt. Consuming 1 kg/s will fully run the Sublimation Station and supply the pufts with some polluted oxygen to spare; the remaining .3kg/s can be composted to supply 180 kg/cycle, more than enough dirt for trees. Burning the ethanol will produce 750g/s of polluted water, or 450 kg/cycle - added to the output from the algae distiller, this produces 642 kg/cycle for a net gain of 82 kg/cycle polluted water.

This loop also produces excess lumber, dirt, algae, and carbon dioxide, as well as a net power gain of ~750W from the generators after powering all the other machines. Adding a fifth distiller to process the excess lumber will increase the net power production to about 1000W and the net polluted water to 132 kg/cycle, and the resulting total carbon dioxide production is enough to feed about 40 slicksters, providing food and Crude Oil or Petroleum.

Sour Gas Boiling (space material zero-inputs)

Sour gas boiling is an upgrade to a petroleum boiler which needs late-game materials and significantly increases the net water and power production. The basic loop of feeding water back into a Oil Well is the same, but the processing apparatus is more complicated. Crude Oil is boiled into Petroleum and then Sour Gas, which is then cooled to yield Sulfur and Methane, the latter of which is heated up again to yield usable Natural Gas.

67% of sour gas converts to methane, while 75% of natural gas becomes polluted water; taken together, 50% of crude oil mass becomes water, compared to the 37.5% conversion via a petroleum boiler. Further, by exploiting rounding in phase transitions (boiling less than 100g of Polluted Water will not produce Dirt), a natural gas generator heated above polluted water's boiling point will essentially produce clean water directly without a water sieve or mass lost as Dirt.

It also produces 33% of input mass as Sulfur, which has no use in the base game but can be processed further in Spaced Out!.

This process needs enormous amounts of heat transfer at extreme temperatures, essentially requiring the use of Super Coolant and Thermium. It also produces considerably less carbon dioxide than petroleum boilers, which can be an issue if relying on Slickster ranching for food.

Sulfur Processing (Spaced Out!)

What you'll need: Divergent ranches; Sludge Press; Sulfur source

Sweetles consume sulfur and excrete 50% of its mass as Sucrose. Grubgrubs fed Sucrose will produce 100% of its mass as Mud (they can also be fed sulfur directly, but only excrete 10% mass - feeding it to sweetles first is thus 5x more efficient). This mud can then be run through a sludge press which will convert 60% of its mass to water and the rest to dirt. The final conversion rate of sulfur to water is thus 30% of sulfur mass.

Sulfur can be renewably obtained from a sour gas boiler or Sulfur Geyser. When combined with a sour gas boiler, this increases the oil to water ratio from 50% to ~60% mass conversion.