In more frivolous and “streamable” systems, resolving survival comes down to rolling a d20. If the check succeeds, the party ate, drank, and moved on; if it fails, a mere cantrip makes the problem disappear. When the adventurers’ hunger and thirst are decided like this, choices, dilemmas, and, above all, agency vanish as well. No risk, no strategy.
In better-designed games, the wilderness environment has rules just as rigorous as those in dungeons. Weather and terrain dictate visibility and pace. Hex navigation has a real and unrelenting cost. We should treat these journeys and explorations as a challenging part of the adventure, not as a mere loading screen before the dungeon.
A character needs a gallon of water, approximately four liters or kilograms, per day in a temperate climate. Imagine in hot climates! Extrapolating for a party of four heroes and two hirelings: nearly 25 liters of water per day. Without pack animals or wagons, the weight of the water alone consumes the carrying capacity needed to bring back gold (XP) from the dungeon. Stopping to hunt can increase the frequency of random encounters. The hunt can yield food and danger. If the hunter takes down a deer, it provides four days of meat; however, the process of smoking and skinning it takes hours upon hours in the same spot, and the smoke and scent of blood can increase the chance of attracting predators.
When they find stagnant water near troglodyte territory, drinking it without boiling or purifying it is an open door to disease.
If the party of adventurers finds poor forage of a few fruits and hard roots, they stave off hunger, but the unpalatable ration can affect the morale or loyalty of the mercenaries the next day.
Spells to purify food and water, and even create water, shouldn’t be seen as a dishonest shortcut, but rather as tough choices. A low-level cleric has few spells per day and is left with a choice: prepare a healing spell or create water? The alternative might lie in mundane equipment like extra waterskins, fishing nets, salt, barrels, and so many others, limited only by the players’ creativity.