How much water do you actually need?
Water is the one thing you cannot go without and the one thing almost everyone underestimates. The math is simple, the storage is cheap, and getting it right is the single most important thing you can do to be ready. Here is the number, and how to hit it.
One gallon, one person, one day. That is the whole formula — multiply it by how many people live in your home and how many days you want to be ready for. For a family of four, three days comes to twelve gallons: about two cases of bottled water plus a few jugs, which takes up roughly the space of a laundry basket.
If anyone in your home has higher needs — someone who is pregnant or nursing, a person managing a medical condition, or anyone in hot weather — plan for more, not less. Water is the cheapest insurance in your whole kit. There is no such thing as too much.
How much to store, by household size.
Three days is where you start. Two weeks is what emergency managers actually recommend for staying home.
| People in your home | 3 days | 2 weeks |
|---|---|---|
| 1 person | 3 gallons | 14 gallons |
| 2 people | 6 gallons | 28 gallons |
| 3 people | 9 gallons | 42 gallons |
| 4 people | 12 gallons | 56 gallons |
| 5 people | 15 gallons | 70 gallons |
Count about half a gallon a day for a cat or small animal, and closer to a full gallon a day for a large dog. Over three days that is roughly a gallon and a half for a cat and three gallons for a big dog. Add it to your total.
Four rules for water that will be there when you need it.
Figure your number first
Use the chart above. Write the total on a sticky note so you know when you are actually done, instead of guessing.
Sealed bottled water is the easy button
Store-bought, unopened bottled water keeps for years — check the date on the bottle. If you fill your own containers, use food-grade jugs and swap the water every six months.
Store it low, and in more than one place
Keep it out of direct sun and away from chemicals or gasoline. Split it across more than one spot so a single fallen shelf cannot wipe out your whole supply.
Keep a way to treat more
Stored water is only half the answer. A filter, purification tablets, or plain unscented bleach with the dosing taped to the bottle lets you make more water safe. This is the cheapest insurance in your kit and the piece most people skip.
Sometimes the tap runs and the water still is not safe.
We picture a water emergency as nothing coming out of the faucet. Just as often, water comes out fine and simply is not safe to drink. A main breaks and pressure drops, or a treatment plant loses power, and the result is a boil-water notice with the tap still running the whole time.
Here is the practical upshot: if the power is out, you probably cannot boil water either. That is the one scenario where stored water and a no-power way to treat it stop being optional. And a notice covers more than drinking — brushing teeth, washing produce, ice makers, and pets all count.
See the full stay-home plan for how water fits with food, power, and sanitation.
Water questions people actually ask.
How long does stored water last?
Sealed store-bought bottled water keeps for years — check the printed date. Water you bottle yourself in food-grade containers should be swapped about every six months.
Can I just refill old milk or juice jugs?
Skip milk jugs — the sugars and proteins are nearly impossible to rinse out and they grow bacteria. Use food-grade water containers or heavy-duty jugs made for the purpose.
How much water for a baby or someone who is nursing?
Plan for more than the one-gallon baseline. Formula needs clean water to mix, and anyone pregnant or nursing needs extra. When in doubt, round up.
What about medical needs?
Some medical equipment and routines need clean water, and dehydration is harder on seniors and people with chronic conditions. If that is your household, treat the chart as a floor and store extra.
Is filtered water enough, or do I need to store it too?
Do both. Stored water covers you immediately with zero effort; a filter or tablets let you extend your supply from other sources. One is your fast answer, the other is your long answer.
Water is step one. Here is the rest.
Tell us who lives in your home and we will build your full kit list — water, food, power, and the rest — with a budget option on every item.