Extra water: pets, heat and dehydrated food
How to add extreme heat, pets and dehydrated food to your emergency water math, with the figures that exist and the ones that don't.
The rule you see most often comes from Ready.gov: at least one gallon of water per person per day, for several days, for drinking and hygiene. Three days is the minimum for the 72-hour kit. It is a reasonable floor, but it says nothing about your particular home. If it is very hot, if you have a dog, or if your pantry is mostly dehydrated food, that gallon falls short.
That is why the water calculator now has three optional adjustments. They come switched off. Here is what each one does and where it comes from.
Very hot weather
FEMA and Ready.gov preparedness guidance says very hot temperatures can double the amount of water needed. If you are in a heat wave, or your house without a fan turns into an oven, turn on Very hot weather and the calculator doubles the people's water. It doesn't double the pets' or the food's, because there is no figure for that.
Pets
There is no single number for animals. Ready.gov asks for extra water depending on size and gives no fixed figure, so in the calculator you type how many pets you have and how many liters each drinks per day. As a starting point, there are references from two US sources:
| Animal size | Water per day, approx. | Source |
|---|---|---|
| 10 pounds (4.5 kg) | one pint, about 0.5 L | Virginia Tech |
| 20 pounds (9 kg) | one quart, about 0.95 L | Rhode Island DEM |
| 50 pounds (23 kg) | half a gallon, about 1.9 L | Rhode Island DEM |
In hot weather animals need more. If you are unsure about your dog or cat, ask your vet: this is planning math, not a prescription.
Dehydrated or freeze-dried food
We found no official figure here either, and it is exactly where people get caught out: a backpacking meal pouch can call for half a liter per serving. In the calculator you type the liters per day for your whole household. Check each package for how much water it needs and add it up. The same goes for anything you cook with water, like rice, pasta or oats, if you plan to eat them in an emergency.
A full example
A family of 4 in very hot weather, at the minimum of one gallon per person, with 2 pets drinking 1 liter each and 2 liters a day to prepare dehydrated food:
- People: 4 × 3.8 L × 2 for the heat = 30.3 L
- Pets: 2 × 1 L = 2 L
- Dehydrated food: 2 L
- Total: 34.3 L a day (9 gallons)
For 3 days that is 103 liters, about 27 gallons: 6 jugs of 20 liters. Without the adjustments, the same family would have stored 45 liters.
And then, storing it well
Now you know how much. It still has to be clean and renewed: how to purify water at home and how much water to store per person cover containers, rotation and timing. In Despendo you can log your jugs like any other item, with a swap date.
Sources and further reading
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