What DC should I use for someone trying to survive indefinitely solely with an alchemy jug as their only source of food and water? (survival campaign)

Question

In a campaign where securing sustenance is part of the challenge, a player with an alchemy jug has decided the party will never have to buy/gather/magically summon food/drink ever again for the rest of the campaign.

They are forgoing other sources sustenance or magic. There are no negative environmental effects beyond the complete lack of food in the surroundings.

The alchemy jug (DMG, 150) provides one of the following quantities of liquid per day:

\begin{array}{c|c} \text{Liquid} & \text{Max Amount} \\ \hline \text{Acid} & \text{8 ounces} \\ \text{Basic poison} & \text{1/2 ounces} \\ \text{Beer} & \text{4 gallons} \\ \text{Honey} & \text{1 gallon} \\ \text{Mayonnaise} & \text{2 gallons} \\ \text{Oil} & \text{1 quart} \\ \text{Vinegar} & \text{2 gallons} \\ \text{Water, fresh} & \text{8 gallons} \\ \text{Water, salt} & \text{12 gallons} \\ \text{Wine} & \text{1 gallon} \\ \end{array}

I don't want to cause the item to be destroyed or lost, but I also don't want goodberry, create food and drink, etc. to be functionally useless.

What DC should I use for someone trying to survive indefinitely solely with an alchemy jug as their only source of food and water? What DC (probably a Constitution check) would I set to discourage excessive use of this behavior?

Campaign Background

Food is not a trivial concern in this campaign. Planar travel is a huge part of the campaign, including destinations where there is lots of water, but not food (certain areas of the plane of water), or lots of food and water but eating the native wildlife carries some issues (like the Beastlands).

Answer 1

Rules-as-Written, the Jug can sustain up to 5 players

The Player's Handbook has explicit rules about food/water consumption you'll want to reference.

Food

A character needs one pound of food per day and can make food last longer by subsisting on half rations. Eating half a pound of food in a day counts as half a day without food.

A character can go without food for a number of days equal to 3 + his or her Constitution modifier (minimum 1). At the end of each day beyond that limit, a character automatically suffers one level of exhaustion.

A normal day of eating resets the count of days without food to zero.

Water

A character needs one gallon of water per day, or two gallons per day if the weather is hot. A character who drinks only half that much water must succeed on a DC 15 Constitution saving throw or suffer one level of exhaustion at the end of the day. A character with access to even less water automatically suffers one level of exhaustion at the end of the day.

If the character already has one or more levels of exhaustion, the character takes two levels in either case.

—Food and Water, Player's Handbook, pg. 185

An alchemy jug is more than capable of producing a gallon per day (up to 8, in fact, of fresh water), and there's no rule that fluids produced by the alchemy jug vanish over time, so in a temperate climate, an Alchemy Jug could produce enough water to sustain 8 humanoids, meaning the excess can be put towards food instead.

A Humanoid must consume at least 1 pound of food to stay nourished, and an Alchemy Jug is capable of producing 1 gallon of Honey, 2 gallons of Mayonnaise, 4 gallons of beer, and 1 gallon of wine. 5th Edition D&D doesn't have rules about Macronutrient balancing, so at least per the rules of the game, 2 gallons of Mayonnaise (or about 16 pounds) is enough to sustain up to 16 creatures per day.

So realistically, a party of up to 5 characters could subsist on nothing but an Alchemy Jug, producing water 2 of every 3 days (5 × 3 = 15 gallons of 16 gallons produced), and producing Mayonnaise every third day (5 × 3 = 15 pounds of 16 pounds produced), with an excess of 1 gallon of water and 1 pound of mayonnaise every third day.

So unless the party is bigger than 5 humanoid creatures, there's no need to call for any kind of checks in the first place. They are fully capable of keeping themselves fed and watered.

So what can you do about it?

I mean, you have to take the Alchemy Jug away if you intend to run a proper survival campaign.

Even if we rule that only the water is nourishing, and that surviving on Honey/Mayonnaise/Beer/Wine doesn't provide enough nutritional value to subsist on (which, if you're running a survival campaign, is not an unreasonable houserule to implement), water is easily the much more difficult substance to obtain. Literally, professional survival guides in the real world emphasize the securing of water to be the second priority, coming only after securing safe shelter from predators/the elements. And in the mechanics of the game, going a single day without water (or even substandard water) is far more taxing than going several days without food.

So an item whose only purpose can only ever be to trivialize that part of the difficulty is always going to be a problem, irrespective of any attempts by the players to also let that item sustain their food needs.

So if you intend to properly restore the survival mechanics of your campaign, you're going to need to remove that item. Talk to your players, explain the issue (and make sure you're all playing the same game), and then, having done all that and having gotten assent from your players, contrive a narrative justification for why the jug is gone or doesn't work anymore.

Answer 2

4 gallons of beer is a lot of beer

You can survive off of beer for a long time. Like, "don't bother tracking it or applying any penalties" long. The jug can comfortably sustain at least 3 Medium creatures and maybe 4 with all of them living an active adventuring lifestyle and not particularly conserving resources (see PHB 185). The beer needs to be very low in alcohol, of course, and preferably high in vitamins/proteins but that isn't a problem (protein) (vitamins) for your alchemy jug except in terms of taste (drinking citrus beer in fall? So tacky).

Now, if your players insist on only drinking modern-style high-alchohol draft beers, there are lots of ways that will kill you, eventually. But there is no reason for your adventurers to do that, unless they are suffering from alcoholism or something.

Answer 3

Using an alchemy jug to produce enough food and water to sustain one creature shouldn't require an ability check.

The basic purpose of the alchemy jug is to produce water and various foodstuffs. The quantities that it produces are obviously sufficient to sustain one creature. There is nothing in the item description to indicate that any ability check is needed to use it. As long as the PC is stating what they are creating with their jug each day, allow them to benefit from their magic item without imposing additional requirements.

Answer 4

Can an alchemy jug produce enough food and water?

Adventurers need 1 pound of food and 1 gallon of water to remove the need to make Constitution saving throws to persist:

Food

A character needs one pound of food per day and can make food last longer by subsisting on half rations. Eating half a pound of food in a day counts as half a day without food.

A character can go without food for a number of days equal to 3 + his or her Constitution modifier (minimum 1). At the end of each day beyond that limit, a character automatically suffers one level of exhaustion. A normal day of eating resets the count of days without food to zero.

Water

A character needs one gallon of water per day, or two gallons per day if the weather is hot. A character who drinks only half that much water must succeed on a DC 15 Constitution saving throw or suffer one level of exhaustion at the end of the day. A character with access to even less water automatically suffers one level of exhaustion at the end of the day.

If the character already has one or more levels of exhaustion, the character takes two levels in either case.

The alchemy jug could produce 2 gallons of fresh water, allowing the adventurer to save 1 gallon for the next day where it produces 1 gallon of honey. 1 gallon of honey weighs 12 pounds, so you could save plenty of honey for the next day when you are creating water.

Since the alchemy jug can provide ample food and water for the adventure, no check is required.

Nutrition question

This may raise the question of whether a person can live off of honey and mayonnaise. Unfortunately, the rules don't make any special mention of nutritional requirements. So by the rules-as-written, the adventurer will be fine.

If you want to add some more realistic elements involving nutrition requirements, a Constitution saving throw would make sense. However, this dives into the realm of house rules, where a number of systems could model nutrition requirements. In this case, it is up to the GM how such rules would be implemented.

Answer 5

Motivation and willpower

The big question here isn't whether the characters would suffer from long-term malnutrition when surviving for months on mayonnaise and honey. The reasonable question to ask is whether they'd be willing to do so if other options are available.

Long before you'd need (or want) to have them make some difficulty checks about health consequences, you'd rather want to impose some penalties or checks for doing arbitrary questing (unless there's a threat that's really immediate and overriding) instead of prioritizing efforts to find food that's simply more pleasant than the boring stuff they have now.

Of course, if they're (for example) literally starving on a liferaft in the middle of the ocean, that's different; but if they're in an open environment where they do have options for spending time and effort to get better food, it's reasonable to expect that whenever they can spare any time and effort for that, they will want to do so.

This is a difficult subject, there's a contradiction between preserving player agency and the metagaming issue of the players having the characters do something that the characters, realistically speaking, really do not want to do.

Food quality - not limited to nutrition, but also taste and variety - is really important for morale and motivation even in difficult conditions. For example, WW1 and WW2 soldier diaries (as well as literature classics e.g. "All Quiet on the Western Front" comes to mind) include so many mentions of various acts showing the importance that warriors in literal life and death situation placed on food specifics (not merely having enough sustenance), that it's implausible to have people simply ignore these for prolonged time.

Answer 6

As an alternative to trying to decide whether or not the survival is or should be possible with the jug, if you're concerned with its use gimping your campaign...

Tax their resources more. Add campaign situations that test the character's generosity. Occasionally, as they try to rely solely on the jug instead of using a combination of spell slots and other resources, introduce other NPCs - a family lost in the wilderness about to starve to death, a war hero lying on the battlefield in need of dressing (could use a lot of water for that), a leper or otherwised diseased/sickly colony that needs fresh clothes (again use a lot of water to wash out the clothes), etc.

This way they can use the jug, but also still have to balance out the other resources and abilities to survive...they'd also have to make sure as they help people that they keep the magical nature of the jug secret or they might have some people try to take it away.