How Much Water to Store Per Person

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“How much water should I store?” is one of the first questions every prepper asks — and getting it right matters, because water is the supply you can least afford to run short on. The answer comes down to a simple formula adjusted for your household. Here is how to calculate exactly how much emergency water to store per person.

The baseline: one gallon per person per day

The widely accepted standard is one gallon of water per person per day. Roughly half of that is for drinking and half for cooking, basic hygiene, and cleaning. This is a minimum for survival and modest comfort — it is not a generous amount, so treat it as the floor rather than the goal. Multiply by the number of people in your household and the number of days you want to be covered, and you have your target.

How many days? Start at 3, build to 14

Emergency agencies have long recommended a three-day (72-hour) minimum, but most preparedness experts now point to two weeks as the realistic target, because serious events — hurricanes, ice storms, water-main breaks, contamination events — can disrupt water for that long. Build to 72 hours first, then work toward 14 days. For a family of four, two weeks at one gallon per person per day is 4 × 14 = 56 gallons.

Adjust for your household

The one-gallon baseline is an average; real needs vary. Increase your storage for hot climates (heat sharply raises drinking needs), for pregnant or nursing women, for anyone who is ill, and for physically active people. Add water for pets — a rough guide is about an ounce per pound of body weight per day for dogs and cats. And remember the gallon-a-day figure is mostly drinking and cooking; if you want water for more thorough hygiene, laundry, or flushing, store more.

Don’t forget non-drinking water needs

It is easy to budget only for drinking and forget that an outage affects everything water touches. Flushing toilets, washing dishes, basic bathing, and cleaning all need water. Many households keep a separate, larger store of non-potable water (which does not need to be drinking-quality) for these uses — for example, filling the bathtub before a forecast storm, or keeping a barrel for sanitation. This keeps your precious drinking water reserved for drinking and cooking.

A simple worksheet

Put it together for your home: number of people × days × 1 gallon = your drinking/cooking target. Add water for pets, extra for heat and special needs, and a separate non-potable reserve for sanitation. Example: two adults, two kids, and a dog, two weeks → 56 gallons for the people, a few more for the dog, plus a sanitation reserve. Write your number down and build toward it. Our guide on how much emergency supply you really need covers food and the rest of your kit.

Storing and maintaining your supply

Once you know your number, store it in food-grade containers, kept cool and dark, and rotate self-filled water every 6 to 12 months — our guide to the best water storage containers covers the how. And because stored water is finite, pair it with a water filter so you can safely extend your supply from other sources if an emergency outlasts what you have stored. Storage plus filtration is what turns a fixed number of gallons into genuine water security.

Count the water you already have

When you tally your supply, remember you start with more water than you think. A typical water heater holds 40 to 50 gallons of usable water (shut off the inlet and draw from the drain valve), and the pipes and toilet tanks (not bowls) in your home hold more. Before a forecast storm, you can also fill the bathtub and spare containers while the supply is still on — a bathtub holds dozens of gallons for flushing and washing. Knowing these reserves exist changes the math: your stored, dedicated drinking water is your front line, but these household sources stretch your sanitation and backup needs considerably.

Build up over time

Reaching a two-week supply can feel daunting if you try to buy it all at once, so build gradually. Add a couple of water containers or a case of bottled water each shopping trip until you hit your number, then maintain it with simple rotation. Storing water is cheap insurance — far cheaper than any other part of your kit — and a steady, incremental approach gets most households to a solid two-week reserve within a few months without straining the budget or your storage space.

Whatever number you land on, write it down and post it with your emergency supplies, along with the date you last rotated the water. Having the target and the rotation date visible turns water storage from a vague intention into a simple, trackable habit — and makes it obvious at a glance when it is time to refresh the supply. And remember that water is the cheapest insurance in your whole kit — it costs almost nothing to store too much, and far too much to store too little when the taps go dry.

Key takeaways

• Store one gallon per person per day — about half drinking, half cooking and hygiene.
• Build to 72 hours first, then to a two-week target (56 gallons for a family of four).
• Add more for heat, pregnancy, illness, activity, and pets.
• Keep a separate non-potable reserve for flushing, washing, and sanitation.
• Pair stored water with a filter so you can extend it if the emergency runs long.

Frequently asked questions

How much water should I store per person? One gallon per person per day, with a two-week supply as the target — so 14 gallons per person.

How much water does a family of four need for two weeks? About 56 gallons (4 people × 14 days × 1 gallon), plus extra for pets and sanitation.

Does that gallon include hygiene? It covers drinking plus basic cooking and hygiene; for fuller hygiene, laundry, or flushing, store additional non-potable water.