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This article is about the Water Filtration Machine as it appears in Subnautica. To see this subject as it appears in Below Zero, click here.

The Water Filtration Machine is a Habitat Compartment that gives the player a stable and consistent supply of water and salt. It can be constructed with the Habitat Builder (Subnautica) and must be wall-mounted in a Multipurpose Room (Subnautica).


A Water Filtration Machine utilizes Energy from the Seabase to desalinate seawater, producing Salt and drinkable water in the form of Large Filtered Water (Subnautica). It takes about 15 minutes and 40 seconds to produce one Large Filtered Water (+50 water) and 7 minutes and 40 seconds to produce one Salt. A single Water Filtration Machine uses 0.85 points of Energy per second, or 51 Energy per minute (taken two or three at a time), and thus can be powered nonstop with four Solar Panels above 100m depth or almost nonstop with one Bioreactor (Subnautica).

Building a Water Filtration Machine has a base Hull Integrity penalty of 1.0 units, and takes up one wall. It will not block the construction of other base components that take up a wall (Windows, Reinforcements, Wall Planters, etc) on the two wall panels to either side. Eight can be built per Multipurpose Room.

The four Storage of a Water Filtration Machine is sectioned into two slots for salt and two for water. If one resource is taken from the machine it will continue operating but generate only that resource: it is not necessary to remove the salt in order for it to make more water or vice versa. It will cease operation once its inventory is filled: in this state it will not draw power from the base.

A Water Filtration Machine can be built above water, but will produce no salt, and only make water at 1/8th of the speed below water.

If powering a Water Filtration Machine with a fuel-using energy source, particularly if using a Bioreactor, note that each Large Filtered Water takes 799 energy to produce: if the machine has been emptied, this means that at a reserve of at least 1,598 energy will be needed to avoid the base running out of power.


Titanium.pngTitanium.pngTitanium.pngCopper Wire.pngAerogel.pngArrow-right (1).pngHabitat Builder.pngArrow-right (1).pngWater Filtration Machine.png

Data Bank Entry


The filtration system draws water unfit for human consumption from an external source, atomically splits it into its constituent parts, and outputs consumable liquid water and salts, while disposing of any harmful by-product. It can be built in any compatible habitat module, but has substantial power requirements.

'The Alterra Water Filtration System: Any liquid into pure, refreshing, pH-balanced water? Yes sir, ANY liquid!'



  • When the Water Filtration Machine was originally added it was extremely cheap to build, requiring only 2 Titanium and nothing else.


This section contains bugs related to Water Filtration Machine (Subnautica). Make sure to only post reproducible bugs, and use appropriate system template ( XboxLogo.png, PlaystationLogo.png, WindowsLogo.png / AppleLogo.png ) depending on which platform(s) the bug has been encountered on.

  • WindowsLogo.png, XboxLogo.png A Water Filtration Machine will block the construction of base modules on the two panels adjacent to it, but not its own panel if the new module generates a corridor. If the player constructs such a module with the machine still in place, the Water Filtration Machine will be deleted and the resources used to make it will be lost.