Rimworld: How to Prevent Food Poisoning
Every Rimworld game has at least one instance of food poisoning; it happens. The trouble comes along when at least one of your pawns is getting food poisoning on a regular basis -- then you have to figure out what about the cooking process is making them sick.
There are several variables that could be affecting the sanitation of your cooking. We're going to go over the three factors that could be causing mass food poisoning in your colony. There are some aspects of the game you're just not going to figure out on your own right away, and this is one of them.
Pawn cooking level
A pawn's cooking level doesn't just affect how quickly it can prepare food and the sorts of foods it's able to make. It also affects how sanitary the food is.
The lower a pawn's cooking level is, the higher the chance the food they will prepare will be contaminated.
A pawn with 1 skill level in cooking has a 10% chance to prepare sickness-inducing foods, while a pawn that's at cooking level 9 has a mere 0.30% chance for their foods to cause food poisoning. The chance continues to dwindle as you get into the higher levels.
This is one good reason to always start a new game with at least one pawn with cooking above level 4.
Room sanitation: AKA separate the stove and butcher table
There are a lot of ways for your kitchen to get contaminated with harmful bacteria, but the most common source is a newbie trap: using one room to house your stove and butcher's table.
This took me a little while to realize when I first started playing Rimworld many moons ago because it just seems like the two stations should be near each other -- and they should. They just should not be in the same room. Put your stove and your butcher table in separate rooms.
Butchering animals gets blood all over the floor, and that is the opposite of cleanliness. While you could take the time to manually order a pawn to clean the blood up after butchering, that is simply not a viable way to deal with the problem. You're never going to be able to catch it all the time.
The simplest solution to this issue is to simply have each station in its own room next to the other, attached to or near the freezer.
Above is an example of what I mean, from a pre-1.0 save (so my mods broke). You can have the two rooms connected via door, but I chose not to in the pictured save game. The two doors to the bottom lead to the freezer.
Animal blood is the number one food contaminant for new players and just separating the two stations fixes the issue. However, if you're having a massive food poisoning outbreak, it's probably because of something even more obtuse.
Minimize foot traffic into the freezer
Pawns track dirt behind them as they walk, which can contaminate food. You can further lower the chances of your pawns getting food poisoning by lowering the foot traffic to your freezer.
There are some ways to do this creatively, such as setting up 1-tile refrigerated rooms to store one pile of meals across your base (creative, but not particularly efficient); but the best way is to download the Rimfridge mod.
Rimfridge adds three refrigerators you can place around your colony, rather than having to rely on manual freezers. I highly recommend it, especially if you have frequent foot poisoning issues.
The ingredients or meal went bad
It just happens sometimes.
Sometimes your pawns will end up cooking some food and it perishes mid-cook, sometimes they are starving and grab up rotten meals just to quell the rumbling in their stomachs. In some instances, just eating raw vegetables gets them sick. A pawn's gotta eat.
You can click on a pawn and see what caused them food poisoning. Usually, it's just a case of bad luck, but sometimes it is caused by plain ol' rotten food. If you have multiple pawns get food poisoning, you need to check what made them sick and try to root out the exact source.
There's not much you can do once your pawns get food poisoning, and their frequent vomiting contaminates all areas of the colony -- and if they vomit on ingredients or straight up meals, those things are contaminated too.
Really, the best thing you can do for your colony's hygiene is separate your butcher table and stove. People hurling their lunch up should be one of the least of your problems, so just take the right precautions and focus on those future raids rolling through your area. Welcome to Rimworld!