The Complete Beginner's Completely Incomplete Guide to Oxygen Not Included
GETTING (MORE) WATER
Sooner or later you will run low on water. Maybe you're reading this because your base is already critically low on water. So maybe I should hurry up and get to it.
We'll start with liquid you will have lying around the map, and how to turn that into water. Then cover vents and geysers with various liquids and how to make them the right temperature, either heating or cooling them.
(A note on my general ignorance: there are both vents and geysers in Oxygen Not Included. I tend to forget this and often use "geyser" even when I'm talking about a vent. Don't let that confuse you, it's just me being sloppy.)
Turning not-water into water
Your starting map will probably have pools of different kinds of liquids. In addition to water, look for polluted water, salt water and brine. These can all be turned into water by sending them through the correct machines.
Polluted water is turned into water by sending it through a water sieve (found under Refinement)
Salt water and brine are turned into water by sending them through a desalinator (found under Refinement)
The "wrong" kinds of liquids won't damage the machines. Water and polluted water will both pass straight through a desalinator without damaging it. Salt water, brine and water will pass straight through a water sieve without damaging it.
So if you have a mixture of liquids pooled together, you can chain a water sieve and desalinator one after the other and pump all liquids through the same pipes. A mixture of stuff will go in, but only water will come out.
A desalinator and a water sieve. You can pump water, polluted water, salt water and brine in through the left and get only water out the right, without damaging the machines.
There are two things to keep in mind when turning non-water into water: germs and temperature
Regarding germs. In general, all liquids you find "lying around" will be germ-free. Also, most vents output germ-free liquids; the exception being the polluted water vent (the normal temperature one, not the cool one).
If you have any polluted water that is the result of a dupe "accident" or vomiting, then that will have germs in it. Those germs will also spread to nearby liquids. (Dealing with germy water is a separate thing, covered in the section on recycling toilet water.)
Regarding temperature. The freezing point of polluted water and salt water is lower than the freezing point of water. If you pump freezing (below +-0C) salt water or polluted water through a desalinator or water sieve, you can end up breaking your pipes in the refining process.
At the other extreme are really hot liquids. You want to be careful with pumping any near-boiling liquids around your base as they will heat up the place.
Let's cover heating and cooling separately, and throw in some sub-headings to give it all a bit of gravitas.
Cool geysers and heating liquids
A cool salt slush geyser. It produces -10C germ-free salt water
A cool slush geyser. It produces -10C polluted (but germ-free) water
The Liquid Tepidizer (found under Utilities)
In general, heating things up is easier than cooling them down. So if your problem is liquid that is too cold then you have the nicer kind of problem.
A common time you would face this is if you have a cool slush geyser or a cool salt slush geyser. They output liquids that are -10C. (Both output germ-free liquid.)
Before turning them into water you will want to heat up the liquids at least enough that they won't break the pipes once they become water.
The freezing point of water is -0.6C. Avoid sending any liquids that are below that through any refining machines, as once they turn into water they can instead turn into ice and break pipes.
(My understanding is that the game actually adds a couple of degrees to all state change temperatures, in order to keep things from flashing back and forth between water and ice. Which would mean you're safe until -2.6C.)
The good news is that if you have liquid that is too cold, that means you have free cooling available. So you can for instance snake cold water from a cool geyser around your base and cool down your base while heating up the water. The bad news is that it isn't easy to control that process - how cold an area will get or how hot the water will get.
Over time you might pump enough freezing water through your base that it becomes freezing cold, too. But this is an easy early-game solution to cooling down your base, and something you can replace with a more controlled cooling loop later. (Cooling loops are covered later in the guide.)
You can also use liquid from a cool slush geyser or cool salt slush geyser to feed a metal refinery, as they require cooling liquid for each use. If you send in liquid from a cool geyser, the liquid the metal refinery outputs will be pretty close to suitable temperature when it comes out, so you can probably just turn it to water and pump it into your water supply. (How much the metal refinery heats up its cooling liquid depends on what metal you refine.)
A more controlled way to heat liquids is with a Liquid Tepidizer. Note that it requres a fair bit of electricity: 960W.
You can have a small box of liquid with a liquid tepizider hooked up to a thermo sensor (found under automation). Then you can set the thermo sensor to whatever minimum temperature you want your liquids to come out at. (Use radiant pipes to improve temperature transfer.)
Having something like this before your desalinator or water sieve should ensure no pipes will break. (I made the box in the example large for clarity; it can be smaller.)
Ensuring a minimum temperature. The thermo sensor makes sure the liquid in the box doesn't go below your preferred minimum temperature.
(Note: To avoid damaging the pipes, I'd recommend using insulated pipes on the side the cool liquid is coming in from.)
Hot geysers and cooling liquids
The polluted water vent. Output: +30C germy, polluted water
The water geyser. Output: +95C water
The salt water geyser. Output: +95C salt water
In addition to the cool geysers covered earlier, there are different kinds of geysers and vents that output hot(ter) water, or liquids that can be turned into water.
My personal favourite is the polluted water vent. It outputs germy, polluted water at +30C. Its output can be used as-is for Thimble Reed farming or turned into water of a very reasonable temperature - your basic plants like Mealwood and Bristle Blossoms stop growing at above +30C. (Turning germy, polluted water into germ-free water is covered earlier in this guide.)
The other geysers that can give you water, and their output temperatures, are:
The water geyser outputs water at +95C
The salt water geyser outputs salt water at +95C
The cool steam vent sounds promising, but the word "cool" refers to steam, so isn't really that cool: +110C
The steam vent outputs steam at a whopping +500C
Perhaps the easiest use of these is the water geyser used to feed a SPOM (which produces oxygen - covered later in this guide).
If you build your SPOM near the water geyser (or salt water geyser) then you won't risk heating up your base too much by piping hot water around. (And remember to use insulated liquid pipes.)
If you dig out an area around and under your water or salt water geyser, you can line it with insulated tiles and then pump out all the gases to create a vacuum in the liquid storage area. That way you will have minimal temperature transfer from your hot liquid(s) to the surrounding area.
(To create a vacuum you can either wall the area off with a gas pump built in that will create a vacuum and then be left in the room, or you can build a liquid lock to allow for access to deconstruct the pump when you're done.)
If you pump hot water to you main water storage then cooling might be necessary.
I tend to avoid filling my water storage with very hot water, but that's easy for me to say as I usually have small bases with few dupes, so I don't need that much water. Regardless, to keep your water storage of a suitable temperature you can run a cooling loop through it.
Another option for cooling, if you have ice or snow on your map, is to store it in your water storage. (Note: it takes a long time for a storage bin full of ice to melt.) You can also use polluted ice to cool down your water, just remember it will turn to polluted water when it melts.
If you have a cool slush geyser of some kind then you could use that to cool down hot liquids, while heating up the slush.
If you have plants that need water of a particular temperature, then in addition to (or rather than) making your whole water supply of that temperature (e.g. under +30C for Bristle Blossoms) you can also just cool down the liquid as you need it, before it gets to the plants in question. This will probably require (a lot) less power.
The steam vent. Output: +500C steam
The cool steam vent. Output: +110C steam
There are two steam vents, the cool steam vent and the steam vent. Both can be used to get (very) hot water. The steam vent will even give you some power in the process.
The steam vent. If you need to use a steam vent for water, then (when the vent is dormant) create a vacuum chamber around it, with insulated walls. Then put a few (two or more) (If memory serves, two is enough) steam turbines above it. Note: the steam turbines will need some form of cooling, as they will get hot quickly.
The steam vent outputs +500C steam. The steam turbines will generate power (as long as the steam is above +125C) and +95C water. (You will need to build liquid pipes from the steam turbine to wherever you want the water to go.)
The cool steam vent. The cool steam vent generates steam that is too cool to power a steam turbine. Instead, you will need to cool it straight down to water by injecting cooling.
There are a few ways you can do this. When looking at the pictures included here, keep in mind that I'm not a min-maxer; I'm satisfied as long as something works. Meaning you can probably find more efficient builds elsewhere.
In both cases, start by creating a vacuum around the vent. Both options use cooling loops for the cooling of the steam. Cooling loops are covered later in the guide.
One option, which I don't use myself but I saw the idea in a Francis John YouTube video, is to have a cooling loop that cools a section outside the cool steam vent chamber. Then you use automation to open and close a door between the two areas to regulate temperature transfer between them. (When the door is open that area will be a vacuum, and so no temperature transfer will take place.)
Use materials with a high thermal conductivity rating for the door and the tiles (walls) on either side of it. E.g. steel for the door and diamond (or metal tiles if you don't have diamond) for the walls. (Temperature transfer basics are covered elsewhere in the guide.)
Another option is to have a cooling loop that runs by the vent, cooling the steam as it comes out.
Note: the liquid in your cooling loop can get very hot, potentially above water's boiling point. So a liquid that can handle +100C is recommended, for instance oil or petroleum.
In both of the approaches covered above the radiant liquid pipes would be run through a thermo aquatuner to be cooled. (How that works is covered in the section on cooling loops.)
In either approach, you can then have a liquid pump (made from gold or steel - it needs to be able to handle near-boiling temperatures) hooked up to a hydrosensor to activate it when there is a sufficient amount of water stored. Also, if you have any diamond to spare, a diamond temp shift plate by the cooling loop will help temperature transfer.
Getting the water a cool steam vent outputs down to a nice, +30 or so temperature would require a lot of cooling and a lot of electricity. Consider, instead, just cooling it down as needed.
If, for instance, you are feeding a SPOM, then cooling it down below +70 isn't that useful. This is because the SPOM outputs gases at a minimum of +70C regardless of the input temperature of the water.
I'll finish up this section with such an example from one of my playthroughs: feeding a SPOM.
Tapping into a cool steam vent. The thermo aquatuner is set to 70 degrees. There's enough space to store a bunch of water under the cool steam vent, and the area is in a vacuum. Water is pumped straight to the SPOM, using insulated liquid pipes to limit temperature transfer.