Government of Canada guidance is about 4 litres of water per person per day: 2 litres to drink, plus 2 litres for food preparation, hygiene and dishwashing. US agencies recommend one US gallon (3.8 litres) per person per day, which is nearly the same amount.
Water is the heaviest and bulkiest part of any emergency supply, and it is the figure that checklists quote least consistently. Some say 2 litres a day, some say 4, and American sources say a gallon. The numbers agree once you separate drinking water from total water.
What the official sources say
The Government of Canada's emergency kit page says "about four litres per person, per day." Its FAQ explains that the amount covers drinking, food preparation, personal hygiene and dishwashing. The older federal list, still reproduced by many municipalities, breaks it into two litres to drink and two additional litres for cooking and cleaning.
| Source | Per person, per day | What it covers |
|---|---|---|
| Government of Canada (drinking) | 2 L | Drinking only |
| Government of Canada (total) | About 4 L | Drinking, food preparation, personal hygiene and dishwashing |
| Ready.gov, American Red Cross, CDC | 1 US gallon (3.8 L) | Drinking and sanitation |
| Sphere humanitarian standard | 15 L minimum | Drinking, cooking and personal hygiene in a relief setting |
The Sphere figure is included for context. It is the minimum that aid agencies plan for when a whole community has lost its water supply, and it shows how tight the household figures are. Four litres a day keeps you hydrated and fed. It does not cover showers, laundry or flushing toilets.
You will see lower numbers on some checklists. We plan to the federal figures: 2 litres to drink, 4 litres in total.
How much to store for your household
The table uses the Canadian total of 4 litres per person per day. The figure in brackets is the drinking-only amount at 2 litres per day.
| People | 3 days | 7 days | 14 days |
|---|---|---|---|
| 1 | 12 L (6 L to drink) | 28 L (14 L to drink) | 56 L (28 L to drink) |
| 2 | 24 L (12 L to drink) | 56 L (28 L to drink) | 112 L (56 L to drink) |
| 4 | 48 L (24 L to drink) | 112 L (56 L to drink) | 224 L (112 L to drink) |
One litre of water weighs one kilogram, so the litre figure is also the weight in kilograms before packaging. A family of four storing two weeks of water is storing 224 kg. That is manageable in a basement or a closet floor if it is split into containers one person can lift.
Why a go-bag cannot carry it
Three days of drinking water for one adult is 6 kg. The full 4-litre allowance is 12 kg. We suggest keeping an adult go-bag to about 7 to 10 kg all-in, which is our judgement and not an official limit, so the full water guideline will not fit alongside everything else.
This is why pre-made bags carry less than the guideline. Emergency water usually comes in 125 mL pouches, and a typical three-day pack of 12 is 1.5 litres in total, or 0.5 litres a day. That is a quarter of the Canadian drinking figure. It is a useful reserve for an evacuation, and it should not be mistaken for 72 hours of water.
A realistic approach is to split the supply. Carry 1 to 3 litres in the bag with a filter or purification tablets, and keep the rest at home. Our comparison of go-bags and home kits explains what belongs in each.
Storing water at home
The US Centers for Disease Control and Prevention (CDC) describes unopened, commercially bottled water as the safest emergency supply. If you fill your own containers, its advice is straightforward:
- Use food-grade water storage containers and sanitize them before filling.
- Never reuse a container that has held chemicals.
- Label each container with the date you filled it.
- Store water somewhere cool and dark.
- Keep it away from gasoline, solvents and similar products, because vapours can pass through plastic.
Government of Canada guidance is to replace the water in your kit at least once a year, along with food, batteries and medications. Choose a fixed date and refill everything at once.
Several medium containers are easier to live with than one large one. A 20-litre container weighs 20 kg when full, which is a heavy lift on a flight of stairs.
If you want storage and treatment in one purchase, these are the options we make for it.
Pets and other adjustments
The Government of Canada's guidance for pets suggests about 4 litres a day for an average dog and 1 litre a day for an average cat. A household of two adults and one dog should therefore plan for about 12 litres a day, or 36 litres for 72 hours.
Some situations call for more than the baseline. Hot weather, illness, pregnancy and breastfeeding all raise the amount a person needs to drink. Freeze-dried and dehydrated meals need water to prepare, so check the pouch and add that amount to your total. Infant formula made from powder needs safe water too.
When stored water runs out
Beyond about two weeks, stored water stops being practical for most homes. A family of four would need 480 litres for 30 days. Past that point the plan becomes storage plus a way to treat more.
- Boiling is the most reliable way to kill germs. The CDC advises a rolling boil for one minute.
- Portable filters have limits. The CDC notes that most remove parasites and, depending on pore size, bacteria, but not viruses. It recommends combining filtration with disinfection, or boiling.
- Chlorine dioxide tablets are described by the CDC as effective against waterborne pathogens, including Cryptosporidium with prolonged contact time. Ordinary chlorine and iodine do not reliably kill Cryptosporidium.
For the differences between devices, see water filter vs purifier. For a full plan covering boil-water advisories and main breaks, see our water disruption guide. The printable checklist has space to write in your own household total.
Frequently asked questions
Is 2 litres or 4 litres of water per day the right figure for Canada?
Both are correct, and they measure different things. Government of Canada guidance is 2 litres per person per day for drinking and about 4 litres per person per day in total, once food preparation, hygiene and dishwashing are included. Plan your drinking supply at 2 litres and your full home supply at 4.
How much water does a family of four need for 72 hours?
At the Canadian figure of 4 litres per person per day, a family of four needs 48 litres for 72 hours, of which 24 litres is for drinking. That weighs 48 kg, so it belongs in home storage and not in a backpack. Add about 4 litres a day for an average dog and 1 litre a day for an average cat.
How often should stored emergency water be replaced?
Government of Canada guidance is to replace the water in your emergency kit at least once a year. Unopened commercially bottled water is the safest choice for storage, according to the CDC. If you fill your own food-grade containers, label them with the date and keep them cool, dark and away from fuels and solvents.
Sources
- Government of Canada: Emergency kits
- Get Prepared: Frequently asked questions
- Ready.gov: Build a kit
- CDC: How to create and store an emergency water supply
- CDC: Water treatment when hiking, camping or travelling
- Government of Canada: Pets and emergencies
General information only. Follow instructions from local emergency officials, and call 911 in a life-threatening emergency.