You need water to survive. It is recommended to get your hands on a waterskin as soon as possible, as it is the cheapest way to keep hydrated. When beginning at the Rumbling Pass Outpost, it is possible to trade your voucher for a waterskin by visiting the provisioner/quatermaster whose name the undersigned has forgotten.

Be careful: most sources of water are polluted. This will result in you being poisoned if you drink water that was not boiled with a kettle prior to being consumed. Kettles can be made by engineers. They are not to be confused with paint kettles (which look like a cauldron). Kettles to boil water look like a tea pot (an actual kettle).

You can also fill your waterskin with pure water by filling it at a well. There are many types of well, but not all of them work. This is the well that works. It is located due east of Crafters' Hall in Fort Praesidium.

Be sure to click the water (you may want to zoom in by holding Ctrl and rolling your middle-button up). Wells can run out of water. If it does, you will get a message saying so (bottom left of your screen). Try coming back later.

If you are a heathen, you can also get pure water by using some spells, such as Pure Liquid (Paganism) or Bless Water (Divine Arcana).

Foods come in a large variety. Rudimentary food can be purchased at merchants such as tavern owners. If you are not picky, you can also find suspicious food in the trash piles found at various place in the city and the sewers. Some food also spawns, such as apples in the orchard behind the bank of Fort Praesidium.

Most food will be cooked by players and found on Player Vendors. A single skill governs both agriculture and cooking. With it, you can pick up vegetables found in the farms, fields and forrests. Most of these can be eaten raw or cooked. Raw food will not give bonus to your stats, but cooked ones likely will. A lot of vegetables can be made into simple soups when cooked with water using a Cooking pot. Other foods come from cooking meat, obtained through skinning. The amount and type of meat skinned from a corpse will depend on its type and size. While a rat may only give a single piece of vermin food, killing a wild boar will possibly reward with nearly 20 uncooked hams. With the appropriate perks, you can also skin and cook human flesh, though that comes with a very high stigma from other players.

Be sure to stay as fulfilled as possible. This is useful for the buffs food provides (extra health, strength, dexterity or stamina), but for other reasons as well. Eating food will regenerate some Grit, used for healing. Finally, if you become too hungry (Somewhere between 40%-60%) you will start taking damage from hunger. If your hunger or thirst ever falls to 0, you risk Permanent Death.

Many food systems are yet to be implemented or fixed (such as apple picking, chicken eggs, etc.). So if you can't find something, be sure to ask in Discord's Player Help. It's possible it does not exist yet.