Quick answer: Store at least one gallon of water per person per day, for drinking and basic hygiene, for at least 3 days; FEMA suggests a two-week supply at home if you can. A family of four therefore needs 12 gallons for three days and 56 gallons for two weeks. Because water is heavy and bulky, pair a modest stored supply with a filter or purifier that can treat rain, well, pool or creek water when storage runs out.
Water is the first item on every emergency list, from FEMA to the UK's new Be Ready campaign. It is also the item people most often get wrong: too little, stored badly, or with no plan for day four. This guide covers the numbers, safe storage, and the filters that stretch a small supply into weeks.
In this guide
- How Much Water Per Person Per Day
- How Much to Store: 3 Days, 2 Weeks, 30 Days
- How to Store Water Safely
- Hidden Water Already in Your Home
- Hygiene and Sanitation Without Running Water
- When a Filter Beats Storage
- Filter Types Compared
- Emergency Disinfection: Boiling and Bleach
How Much Water Per Person Per Day
The US standard from Ready.gov and the CDC is one gallon (about 3.8 liters) per person per day: roughly half a gallon to drink and the rest for food preparation and hygiene. Store more for:
- Hot climates and summer emergencies (needs can double)
- Children, nursing mothers and people who are sick
- Pets (about an ounce per pound of body weight a day for dogs and cats is a common rule of thumb)
- Freeze-dried food, which needs about a cup of water a serving
How Much to Store: 3 Days, 2 Weeks, 30 Days
| Household | 3 days | 2 weeks | 30 days | 30-day weight |
| 1 person | 3 gal | 14 gal | 30 gal | about 250 lb |
| 2 people | 6 gal | 28 gal | 60 gal | about 500 lb |
| 4 people | 12 gal | 56 gal | 120 gal | about 1,000 lb |
| 4 people + dog | about 14 gal | about 63 gal | about 135 gal | about 1,130 lb |
Water weighs about 8.3 pounds a gallon. Three days is easy for almost anyone. Two weeks takes planning and floor space. Thirty days for a family is more than most homes can store, which is why the second half of this guide is about filters.
How to Store Water Safely
- Commercial bottled water is the simplest. Keep it sealed, in a cool, dark place, and use it by the date on the label.
- Food-grade containers if you fill your own. Clean and sanitize them first, fill from a safe tap, and cap tightly. The CDC recommends replacing home-filled water every six months.
- Never reuse milk or juice jugs (proteins and sugars are hard to clean out) or containers that held chemicals.
- Keep containers off concrete and away from fuel, solvents and pesticides; plastic can absorb vapors.
- Label every container with the fill date.
Containers we carry: the Coghlans Collapsible Water Container (5 gallons) and Expandable Camp Jug store flat when empty. For 55-gallon drums and stackable tanks, read our water storage container guide.
To keep stored water fresh longer, Aquamira Chlorine Dioxide Water Treatment treats up to 60 gallons; the maker states that treated water left sealed has a five-year shelf life.
Hidden Water Already in Your Home
- Water heater: typically 30–80 gallons. Turn off the power or gas first, let it cool, then drain from the valve at the bottom.
- Pipes: open the highest faucet, then drain from the lowest.
- Ice in the freezer.
- Toilet tank (not the bowl) if you do not use chemical cleaners in it. Treat before drinking.
- Pools, rain barrels, creeks and ponds: not safe to drink untreated, but excellent sources if you can filter or purify them.
Hygiene and Sanitation Without Running Water
The gallon-a-day figure includes basic hygiene, but sanitation is where water disappears fastest. A single toilet flush uses 1.5 gallons or more. Stretch your supply:
- Toilets: if the water is off but the sewer works, flush by pouring a bucket of non-drinking water (pool, rain, gray water) into the bowl. If sewers back up, line the toilet or a bucket with heavy trash bags and use cat litter or sawdust.
- Hands: hand sanitizer for routine use; save water for washing before food prep and after the toilet.
- Dishes: paper plates and cups, or wipe dishes before a small rinse.
- Bathing: wet wipes and a basin wash instead of a shower.
- Keep it separate: mark containers for drinking and for non-drinking use so they are never confused.
When a Filter Beats Storage
A family needs about a ton of stored water to last 30 days. A household gravity purifier weighs under two pounds and can treat thousands of liters. Storage covers the first days and the times when no source is available; a filter covers everything after that.
Filter vs purifier. A filter removes bacteria (such as E. coli and Salmonella) and parasites (such as Giardia and Cryptosporidium). A purifier also removes or inactivates viruses (such as Rotavirus and Hepatitis A). Viruses are a real risk in flood water and surface water near people or livestock, and after a sewage system fails. Filters do not remove dissolved chemicals unless they include carbon, and none of them make salt water drinkable.
Filter Types Compared
Specifications below come from each product page.
| Product | Type | Removes viruses | Rated life | Flow / speed | Price |
| LifeStraw Escape | Pressurized tank, 20 L | Yes, 99.99% | 18,000 L (ultrafilter); 600 L carbon | 1+ L a minute | $329.95 |
| LifeStraw Peak Gravity Purifier 8L | Gravity purifier | Yes | 18,000 L | 30 L an hour | $189.95 |
| Guzzle H2O Stealth Home | Under-sink UV-C + carbon (needs power) | Yes, 99.99% (UV-C) | 1,000 gal a carbon cartridge | 2.2 gal a minute | from $645 |
| Grayl GeoPress | Press bottle | Yes, 99.99% | 250 L a cartridge | 24 oz in 8 seconds | $99.95 |
| LifeStraw Peak 8L Gravity Filter System | Gravity filter + storage bag | No | 2,000 L | Fast gravity | $149.95 |
| Sawyer One Gallon Gravity | Gravity filter | No | Up to 100,000 gal | 1 gal in about 7 min | $46.99 |
| Sawyer Squeeze | Squeeze / inline, 0.1 micron | No | Lifetime warranty | Squeeze speed | $45.99 |
| LifeStraw Peak Straw | Straw, 0.2 micron | No | 4,000 L | Sip | $24.95 |
| Puribag Pro System | Chemical sachets + hollow-fiber filter | Yes (sachets and filter) | 120 L sachets; 5,000 L filter | 10 L batches | $69.99 |
Our picks: for a household, a virus-rated gravity or pressurized purifier (Escape or Peak Gravity Purifier) plus a Sawyer Squeeze per person for go bags. For a deeper comparison, read our 2026 water purification comparison and LifeStraw vs Sawyer Mini. Shop all water filtration and purification.
Cold weather tip: hollow-fiber filters (Sawyer, LifeStraw membranes) can be damaged if they freeze after use. Keep a used filter in an inside pocket or a heated room in winter, and replace one you suspect has frozen.
Emergency Disinfection: Boiling and Bleach
If you have no filter, the US EPA gives two methods:
| Method | How | Notes |
| Boiling (best) | Bring to a rolling boil for 1 minute; 3 minutes above 6,500 feet. Let cool. | Kills bacteria, parasites and viruses. Does not remove chemicals. |
| Unscented household bleach, 6% | 8 drops (about 1/8 teaspoon) per gallon; stir and wait 30 minutes | Double the dose if the water is cloudy, colored or very cold. Water should have a slight chlorine smell. |
| Unscented household bleach, 8.25% | 6 drops per gallon; stir and wait 30 minutes | Do not use scented, color-safe or splash-less bleach. |
| Tablets or drops | Follow the label | E.g. Coghlans tablets (2 tablets a quart) or Aquamira. |
Our guide to purification tablets and drops covers the chemistry in detail.
Common Questions
How much water should I store per person?
At least one gallon per person per day, for at least three days. FEMA suggests two weeks for a home supply if you have the space.
How long does stored water last?
Commercial bottled water lasts until its printed date. The CDC recommends replacing home-filled water every six months. Water treated with a stabilizer such as Aquamira chlorine dioxide is rated by the maker for up to five years sealed.
Is it better to store water or buy a filter?
Both. Stored water covers the first days and situations where you cannot reach a source. A filter or purifier covers everything after that and takes up almost no space.
Do I need a purifier or is a filter enough?
A filter handles bacteria and parasites, which is enough for clear tap or well water. Choose a purifier if you may drink flood water, surface water near people or animals, or water after a sewage failure.
Can I drink water from my water heater?
Yes, in an emergency. Turn off the power or gas, let it cool, and drain from the bottom valve. Filter or treat it if it looks rusty or cloudy.
How much water does freeze-dried food need?
About one cup per serving. ReadyWise lists about 100 cups for its 14-day bucket, so count cooking water in your plan.
