Guides · Water

How much water to store at home

Water goes first, because it's the one thing you can't go without. The good news: it's cheap, it's simple, and one afternoon sorts it.

How much

The usual figure, from Ready.gov, is 3.8 litres (1 US gallon) per person per day, for drinking and basic washing. Store more in a hot climate or a hot spell, and for anyone who is pregnant, breastfeeding, unwell, or very young or old.

People	1	2	3	4	5	6
3 days	11.4 L / 3 gal	23 L / 6 gal	34 L / 9 gal	46 L / 12 gal	57 L / 15 gal	68 L / 18 gal
7 days	27 L / 7 gal	53 L / 14 gal	80 L / 21 gal	106 L / 28 gal	133 L / 35 gal	160 L / 42 gal

Pets need water too: add theirs.

What to keep it in

Bought bottled water keeps until its date. It's the easiest start.
Food-grade water containers with a tap or spout. 20 L (about 5 gal) is as much as most people can lift and pour. Full, it weighs just over 20 kg (44 lb).
Never reuse a container that held chemicals, such as bleach, cleaners or garden sprays. Milk and juice bottles are hard to clean properly, so don't use those either.

Filling your own

Wash the container and lid with dishwashing liquid, and rinse.
Sanitise it: mix 1 teaspoon of unscented household bleach (5 to 9 percent; if yours is weaker, follow its label's sanitising directions) into about 1 litre (1 quart) of water, put the lid on and shake so it touches every inside surface. Wait at least 30 seconds, pour it out, and let the container air dry before you fill it (the US CDC's method).
Fill it from a treated public supply. Water from a tank or well needs treating first (below).
Cap it tightly and label it "Drinking water" with the date.
Every 6 months, use it for washing or the garden, then clean and refill.

Where to keep it

Cool and dark, ideally 10 to 21 °C (50 to 70 °F): out of the sun, away from heaters, never in a hot garage, car or shed.
Away from petrol, paint, pesticides and other chemicals, which can taint plastic. A board or pallet under it keeps it clean and off a cold or damp floor.
Lids on, always. A small child can drown in a few centimetres of water. Keep every bucket, drum and container covered. Covered water also stops mosquitoes breeding.

Water you already have

Before you open the stored water, use what's in the house already: ice and frozen bottles from the freezer, and the liquid in tinned fruit and vegetables. The hot water cylinder holds a lot (often 100 to 300 L, 26 to 79 gal): ask your plumber or installer now how to draw from it safely with the power and gas off, and write it down. Never drink water from radiators or the central heating system.

Making more water safe

For when stored water runs low and you have water you're not sure about. If your water authority or health department gives instructions, follow theirs first. The amounts are the US CDC's. If the water is cloudy, let it settle and pour off the clear water, or strain it through a clean cloth or coffee filter first.

Method	How	Notes
Boil	A rolling boil for 1 minute (3 minutes above 1,980 m / 6,500 ft). Cool, then store covered.	The safest way to kill germs. Uses fuel. Doesn't remove chemicals.
Bleach	Unscented household bleach, 5 to 9 percent: 2 drops per litre, or 8 drops per US gallon. Double it for cloudy or very cold water. Stir, and wait at least 30 minutes. The water should smell faintly of bleach. If it doesn't, add the same amount again and wait another 15 minutes. If it still doesn't, don't drink it.	Kills most bacteria and viruses. Doesn't work as well as boiling on some parasites, such as Cryptosporidium and Giardia. Bleach slowly loses strength once opened, so date the bottle and replace it about once a year.

Check the strength on the label. The CDC amounts are for 5 to 9 percent bleach, the usual US strength. Household bleach in many other countries is weaker, often 2 to 4 percent, and weaker bleach needs more. If the label gives directions for treating drinking water, follow them; if not, ask your local health authority, and boil instead.

Never use scented, colour-safe or "with added cleaners" bleach, or water that smells of fuel or chemicals. Boiling and bleach won't fix it.

Tick list

Drinking water for everyone, for 3 days at least
Every container labelled and dated
A reminder in the calendar to swap it in 6 months
Unscented bleach of known strength, and a dropper, dated, kept up high and out of children's reach
A pot with a lid, for boiling on an outdoor barbecue or camp stove

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More guides

Sources

Ready.gov (US FEMA), Water: https://www.ready.gov/water
US CDC, How to Create an Emergency Water Supply: https://www.cdc.gov/water-emergency/about/how-to-create-and-store-an-emergency-water-supply.html
US CDC, How to Make Water Safe in an Emergency: https://www.cdc.gov/water-emergency/about/index.html

Heath is an AI preparedness guide, made by someone prepping in Tasmania. This guide was written with AI from official guidance. It's general information for getting ready at home, not professional advice. In an emergency, follow your official emergency services first.