How Much Emergency Water Per Person? 3-Day Amounts by Household Size
TL;DR
- Plan on about 1 gallon (roughly 4 liters) of water per person per day for drinking, cooking and hygiene, and store at least 3 days.
- A family of four needs 12 gallons (48 liters) for 3 days. A single 6-pack of 2-liter bottles lasts that family less than a day.
- Hot weather, children, nursing mothers and sick people can double the need.
- Safe-Life's October update raised its water standard from 1 to 4 liters per person per day, so the same bag now shows about a quarter of the water days.
How much water is in your emergency kit right now? For most people it is a few small bottles or one or two big ones. Work out how many days that actually covers and the answer is usually much shorter than expected.
About 1 gallon (4 liters) per person per day, for at least 3 days. A family of four needs 12 gallons.
Why 1 gallon a day
An adult typically drinks 2 to 2.5 liters a day. Add water for cooking, washing hands and brushing teeth, and you get to roughly 4 liters, or about a gallon.
| Measure | Per person per day | What it covers |
|---|---|---|
| Drinking only | 2-2.5 L | Typical daily intake |
| Storage target | 1 gal (3.8 L) / 4 L | Drinking + cooking, washing, sanitation |
FEMA recommends at least one gallon per person per day for several days, for drinking and sanitation. Korean local government disaster guides (for example Chungju City) use the same figure in metric: 4 liters per person per day.
For how many days, the usual baseline is 3 days for a go bag. If you may need to shelter at home, Korea's national safety portal Safety Korea 24 asks households to keep supplies for two weeks.
Storage by household size
At 1 gallon per person per day:
| Household | 3 days | 1 week | 2 weeks |
|---|---|---|---|
| 1 person | 3 gal (12 L) | 7 gal (28 L) | 14 gal (56 L) |
| 2 people | 6 gal (24 L) | 14 gal (56 L) | 28 gal (112 L) |
| 3 people | 9 gal (36 L) | 21 gal (84 L) | 42 gal (168 L) |
| 4 people | 12 gal (48 L) | 28 gal (112 L) | 56 gal (224 L) |
In bottles you can actually buy:
- One 6-pack of 2-liter bottles (12 L) = one person for 3 days. For a family of four, it lasts about 18 hours.
- A family of four for 3 days = four 6-packs of 2-liter bottles, or twelve 1-gallon jugs. That fits next to the front door.
- A family of four for 2 weeks = 56 gallons. Build that up over time as a home supply rather than buying it all at once.
When you need more
FEMA notes that in very hot temperatures, water needs can double. Plan above the table if:
- It is summer, or a power outage has cut your air conditioning
- Someone in the home is a child, nursing, pregnant or sick
- You have an infant on formula (count formula water separately)
- You have pets
If water runs short, protect drinking water first. Wet wipes and hand sanitizer can stand in for some washing water; nothing stands in for drinking water.
Storing and rotating
- Keep commercially bottled water sealed in a cool, dark place. Drink it before the date on the label and replace it, so nothing goes to waste.
- Water you bottle yourself goes in clean food-grade containers and should be replaced every six months.
- If a water outage is announced, fill the bathtub and buckets. Use that for washing and flushing, and keep bottled water for drinking.
- Do not keep it all in one place. Put about one day of drinking water per person in the go bag (a bag you cannot run with is no use) and keep the rest as a home supply.
Why Safe-Life changed its water standard to 4 liters
Safe-Life is an app that works out how many days the water and food in your emergency kit will last. It used to count water at 1 liter per person per day, which falls short even for drinking alone.
The October update (v2.0) raised the standards to 4 liters of water and 2,100 calories of food per person per day. The food figure is the emergency planning figure from the Sphere Handbook, the international humanitarian standard.
Your items stay the same and only the calculation changed, so the same bag now shows about a quarter of the water days and about half the food days. The smaller number can be a surprise, but the old one was optimistic. The app shows exactly how much you are short, so you can fill the gap.
Open your go bag and count the bottles. That number tells you how many days your household can last.
Sources
- Water - Ready.gov (FEMA): 1 gallon per person per day, double in very hot temperatures, replace self-stored water every six months
- Emergency action guide - Safety Korea 24 (Ministry of the Interior and Safety): 2-3 days of supplies in a bag, two weeks of supplies for sheltering, fill containers before a water outage
- Emergency supplies - Chungju City: 4 liters per person per day, 2-2.5 liters for drinking
- The Sphere Handbook: 2,100 calories per person per day for emergency food planning
FAQ
Do I need to fit a gallon a day per person in my go bag? No. A gallon covers a full day at home, including washing. A bag you have to carry should hold about one day of drinking water per person; keep the rest at home.
Can I store tap or filtered water? Yes. Use clean, food-grade containers, seal them, keep them somewhere cool and dark, and replace the water every six months. Sealed commercial bottled water keeps until the date on the label.
Is bathtub water safe to drink? It is not recommended. A bathtub is not a food-grade container, so use that water for washing and flushing and keep bottled water for drinking.
Is 1 gallon a day an official standard? Yes. It is FEMA's recommendation, and Korean local government guides use the metric equivalent of 4 liters. Korea's national portal gives durations (2-3 days, two weeks) rather than liters.