Ready.gov advises at least one gallon of water per person per day, for several days, for drinking and sanitation. For four people that is 4 gallons a day: 12 gallons for three days and 28 for a week. Children, nursing mothers and sick people may need more, and freeze-dried food needs extra water to prepare.
The standard figure and where it comes from
Ready.gov's water page, read 2026-10-14, recommends at least one gallon of water per person per day for several days, for drinking and sanitation. It does not name a number of days. The same page says a typical person needs about three quarters of a gallon of fluid daily, which is why one gallon is a sensible round figure with room for hygiene.
It also adds the adjustments that matter for a family: children, nursing mothers and sick people need more, hot climates can double needs, and medical emergencies may call for more. It advises against rationing drinking water unless authorities order it.
The math for four people
The arithmetic is 4 people x 1 gallon x number of days.
| Days | Working | Gallons for four |
|---|---|---|
| 1 | 4 x 1 x 1 | 4 |
| 3 | 4 x 1 x 3 | 12 |
| 7 | 4 x 1 x 7 | 28 |
| 14 | 4 x 1 x 14 | 56 |
| 30 | 4 x 1 x 30 | 120 |
A 30-day store of 120 gallons takes real room. If space is limited, you can store a shorter target, such as the 14-day line above, and plan how you would treat water beyond it.
Adjust upward if anyone in the home is a nursing mother, is sick, or if you live somewhere hot. A household with a baby, a teen with high activity or a pregnant adult should treat 4 gallons a day as a floor.
Water that food needs
Dry and freeze-dried food is prepared with water, and this water is in addition to the drinking gallon. My Patriot Supply states the water needed to prepare each of its kits in full:
| Kit (one person) | Water to prepare the whole kit, per the company |
|---|---|
| 72-hour sample pack | 3.57 gallons |
| 2-week | 5.7 gallons |
| 4-week | 9.14 gallons |
| 3-month | 36.12 gallons |
| 1-year | 144.5 gallons |
Those figures are the company's, read on its product pages on 2026-10-14. Four 1-year kits for a family of four would need 4 x 144.5 = 578 gallons to prepare, before any drinking water. Mountain House states about 88 gallons for its 1-year kit, read the same day.
For a short plan, the water for food is a small addition. For a long one it becomes the largest line in the plan, which is one reason the 1-year emergency food supply guide suggests staging the build.
Storing water
Ready.gov, read 2026-10-14, advises commercially bottled water in its original sealed container, stored in a cool, dark place. It says to replace water you bottled yourself every six months.
Practical points that follow from that:
- Buy sealed commercial containers if you can, and keep them where they will not freeze or sit in sun.
- Label home-bottled containers with the fill date and put the six-month check on your calendar.
- Store water in more than one place so a single leak or a blocked room does not remove it.
- Keep the containers somewhere you can lift them safely, because water is heavy.
Making water safe
Two official sources give the same basic treatment steps for water of unknown quality, and Ready.gov also lists distillation:
- Boil. A rolling boil for one minute; the CDC gives three minutes above 6,500 feet (CDC emergency water treatment).
- Unscented household bleach. Ready.gov gives 1/8 teaspoon per gallon, the CDC gives 8 drops per gallon and says to double it if the water is cloudy or cold, and both say to wait 30 minutes. The FDA gives the same figures for 5.25% unscented bleach (FDA).
Follow the label of the bleach you hold and the current guidance from local authorities, which can differ after a flood or contamination event.
What changes the number
- Age. Infants, toddlers and teens differ in how much they drink and in how food is prepared. See the nutrition note for where to check.
- Infant formula. Ready.gov lists ready-to-feed formula first; if you mix powder, it says to use bottled water, and boiled water only as a last resort.
- Climate and activity. Hot weather and heavy work raise needs.
- Pets. Ready.gov says to keep several days of water for pets but gives no quantity.
- Cooking and hygiene. The one-gallon figure already includes sanitation, but a household that cooks with a lot of water or washes often will use more.
How this fits the rest of your plan
Water is the part of a plan that most readers forget until the food is bought. The 72-hour kit guide treats it as a line in the three-day checklist, and the 30-day plan shows how the water for food adds to the 120 gallons above. The food quantities article gives the calories side of the same math.
Our overall guide to an emergency food supply for family of four puts the food, water and cooking pieces together.
What this doesn't cover
This guide does not give medical advice, and it does not rate water filters or purifiers. If someone in your home has a medical condition that affects fluids, check with a clinician.
FAQ
How many gallons of water does a family of four need per day?
Ready.gov advises at least one gallon per person per day, which is 4 gallons a day for four people. It lists more for children, nursing mothers, sick people and hot climates.
How much water for two weeks?
For four people, 4 x 1 x 14 = 56 gallons at the Ready.gov baseline, plus the water to prepare any dry or freeze-dried food.
Does the water for freeze-dried food count toward the one gallon?
No. The one-gallon figure is for drinking and sanitation. Water to prepare food is separate; a company's page states how much its kit needs.
How long does stored water last?
Ready.gov says commercially bottled water, sealed and kept cool and dark, can be stored, and that you should replace water you bottled yourself every six months.
Can I ration water?
Ready.gov says never to ration drinking water unless authorities order it.
Sources
- Ready.gov, water, read 2026-10-14
- CDC, emergency water treatment, read 2026-10-14
- FDA, food and water safety during power outages and floods, read 2026-10-14
- Ready.gov, food, read 2026-10-14
- Ready.gov, pets, read 2026-10-14
- Company product pages for the water-to-prepare figures, read 2026-10-14
Update history
| Date | Change |
|---|---|
| 2026-10-14 | First published |