You can survive weeks without food but only a few days without water, and municipal water is one of the first things to fail in a big storm, flood, or grid outage. A good water plan has three parts: store enough, know your backup sources, and know how to treat what you find.
How much water to store
Emergency-management agencies such as FEMA recommend at least one gallon per person per day, for a minimum of three days, for drinking and basic sanitation. Many preparedness planners aim for two weeks.
| Household | 3 days (minimum) | 14 days |
|---|---|---|
| 1 person | 3 gallons | 14 gallons |
| 2 people | 6 gallons | 28 gallons |
| 4 people | 12 gallons | 56 gallons |
Add more for pets, hot climates, nursing parents, and anyone who is ill. Emergency guidance generally advises against rationing drinking water — cut back on washing instead.
How to store it
- Commercially bottled water: keep it sealed and use it by the printed date.
- Home-filled containers: use food-grade containers made for water storage, label them with the fill date, and replace the water roughly every six months (a commonly recommended interval).
- Where: a cool, dark place, away from gasoline, solvents, and pesticides. Avoid used milk jugs, which degrade and are hard to clean.
Backup sources around the house
- Water heater tank: typically 30–50+ gallons of clean water. Shut off the power or gas supply first, let it cool, and follow the manufacturer's instructions to drain it.
- Melted ice from the freezer, and the water in your pipes if the supply is cut but the pipes are intact.
- Rain: collection rules vary by state and locality, so check yours. Treat it before drinking.
- Streams, ponds, and lakes: treat everything, always.
Making water safe
Start by clarifying cloudy water: let it settle, then pour it through a clean cloth or coffee filter. Then choose a method:
| Method | Handles | Limits |
|---|---|---|
| Boiling | Bacteria, viruses, and protozoa | Needs fuel. Rolling boil for at least 1 minute (3 minutes above roughly 6,500 ft). Doesn't remove chemicals. |
| Filter | Hollow-fiber filters (0.1–0.2 micron) remove bacteria and protozoa such as Giardia and Cryptosporidium | Most filters do not remove viruses unless sold as a "purifier." Look for independent certification such as NSF/ANSI. |
| Chemical treatment | Chlorine dioxide tablets or unscented household bleach inactivate bacteria and viruses | Follow the product label or CDC dosing exactly. Wait times are longer for cold or cloudy water. |
For questionable sources, layer your methods: filter first, then treat chemically, or boil whenever you can.
Looking for filters, storage containers, and purification gear? See our Water page.