Emergency water storage calculator: how much water to store for your household
Last checked: November 1, 2026, against Ready.gov, the CDC, Health Canada, the UK's Be Ready campaign and the Queensland Government. We recheck these every six months, the same day we rotate our own water.
Short answer: in the US, store at least 1 gallon of water per person per day. That's 3 gallons each for 3 days, the minimum, or 14 gallons each for 2 weeks, which the CDC suggests if you can. For a family of four over two weeks, that's 56 gallons (about 212 litres). Store more in a hot climate, for pets, and for anyone pregnant or sick.
Water is the one supply you can't improvise for long, and it's also one of the cheapest to get right. Put your household's numbers in below and you'll have a target, a container count and a date to rotate it.
Water storage calculator
The calculator needs JavaScript. The table below it gives the same answer for the US guideline of 1 gallon per person per day.
How much water to store: the quick table
US guideline, 1 gallon (3.785 litres) per person per day, rounded to the nearest litre.
| People | 3 days | 1 week | 2 weeks |
|---|---|---|---|
| 1 | 3 gal (11 L) | 7 gal (26 L) | 14 gal (53 L) |
| 2 | 6 gal (23 L) | 14 gal (53 L) | 28 gal (106 L) |
| 3 | 9 gal (34 L) | 21 gal (79 L) | 42 gal (159 L) |
| 4 | 12 gal (45 L) | 28 gal (106 L) | 56 gal (212 L) |
| 5 | 15 gal (57 L) | 35 gal (132 L) | 70 gal (265 L) |
| 6 | 18 gal (68 L) | 42 gal (159 L) | 84 gal (318 L) |
Divide the gallons by 5 and round up for the number of 5-gallon jugs. Double the row if you live somewhere very hot.
What each country's official guidance says
| Country | Per person per day | How long | Source |
|---|---|---|---|
| US | At least 1 gallon (about 3.8 L), for drinking and sanitation | At least 3 days; 2 weeks if possible | Ready.gov, CDC |
| Canada | 2 L to drink plus 2 L for cooking and cleaning | At least 72 hours | Health Canada |
| UK | 3 L to drink, plus more for cooking and washing | 3 days | Be Ready |
| Australia (Queensland) | 10 L per person in total | 3 days | Queensland Government |
Why the numbers look different. The UK and Canadian figures split drinking water from the rest. Ready.gov says a normally active person needs about three quarters of a gallon of fluid a day, and the full gallon leaves room for cooking and basic hygiene. If you're unsure, the US gallon is the simplest figure to plan around, and it's close to Canada's 4 litres. In a real emergency, follow your local authorities first.
Storing it so it stays safe
From the CDC:
- Unopened store-bought water is the safest and most reliable. Watch the expiration date.
- Filling your own? Use food-grade containers with tight lids, never glass, and never anything that held bleach, pesticides or other chemicals.
- Clean them first: wash with soap, rinse, then shake with 1 teaspoon of unscented bleach (5% to 9% sodium hypochlorite) in 1 quart of water, wait at least 30 seconds, pour out and air dry.
- Label and date each container "drinking water", keep it at 50 °F to 70 °F (10 °C to 21 °C), out of the sun and away from fuel and chemicals.
- Replace home-filled water every 6 months. The calculator gives you the date.
- Keep a bottle of unscented bleach too, so you can treat more water if you need to.
Don't ration. Ready.gov says to drink what you need today and try to find more for tomorrow.
If your stored water runs low, our guide on how to purify water in an emergency covers boiling, bleach doses by strength, tablets and filters. Water is one line of a wider kit; the other one most people forget is cash for when card machines are down.
Sources
Checked November 1, 2026.
- Ready.gov: Water (1 gallon per person per day, three quarters of a gallon of fluid, needs can double in heat, don't ration)
- CDC: How to Create an Emergency Water Supply (3 days minimum, 2 weeks if possible, containers, cleaning, 6-month replacement, 50 °F to 70 °F)
- Health Canada: Food and drinking water safety in an emergency (2 L plus 2 L per person per day, at least 72 hours, extra for pets)
- UK Government, Be Ready: Be ready for emergencies (3 litres per person per day for drinking)
- Queensland Government: Pack an emergency kit (10 litres per person for 3 days)
Spotted a change in official guidance? Let us know.
Quick answers
How much water should I store per person?
In the US, Ready.gov and the CDC say at least 1 gallon (about 3.8 litres) per person per day, for at least 3 days, and the CDC suggests a 2-week supply if possible. Health Canada says 2 litres to drink plus 2 litres for cooking and cleaning per person per day, for at least 72 hours.
How much water does a family of four need for two weeks?
At the US guideline of 1 gallon per person per day, a family of four needs 56 gallons (about 212 litres) for 14 days. That's twelve 5-gallon containers, and it weighs about 212 kg (467 lb).
How often should I replace stored water?
The CDC says to replace water you filled yourself every 6 months, and to watch the expiration date on store-bought bottled water.
Do I need more water in hot weather?
Yes. Ready.gov says that in very hot temperatures, water needs can double. The CDC also suggests storing more for pregnant women, people who are sick, pets and hot climates.