Calculate household water needs

Paper, a pencil, a calculator and the labeled capacity of any water containers you own. You will not move full containers or cut back anyone's drinking to test the numbers.

CDC advises storing at least 1 US gallon of water per person per day for at least 3 days, and a 2-week supply if you can. One US gallon is about 3.785 liters. The formula is:

people × days × 1 gallon = starting reserve

Keep units consistent. An imperial gallon (about 4.55 liters) is larger than a US gallon, so do not mix them.

The 1-gallon figure covers drinking and basic hygiene for a typical adult. Add more for:

• children who are nursing, people who are pregnant or sick, and anyone in hot weather
• pets (ask your veterinarian for a daily figure)
• cooking dried beans, rice and pasta, which use water for soaking, boiling and washing up
• medical needs, such as equipment cleaning, that a care provider has told you about

Gardens, livestock, laundry and normal toilet flushing use far more water. Calculate those separately so they do not hide inside the emergency number.

A liter of water weighs about 1 kilogram, and a US gallon weighs about 8.3 pounds. A 5-gallon jug weighs over 40 pounds before the container. Check who can lift and pour each size. A reserve that the person at home alone cannot open or pour is not usable during an outage. Smaller jugs, a spigot or a pump may solve that.

Large tanks can be heavy enough to matter for a floor or shelf. Ask the manufacturer or a builder before setting one on an upper floor or an old shelf.

Three people plan for 3 days:

3 × 3 × 1 = 9 US gallons, about 34 liters.

For 14 days:

3 × 14 × 1 = 42 US gallons, about 159 liters.

The household has a dog and cooks dried beans. They write "plus dog, plus bean cooking" beside both numbers so no one mistakes 9 gallons for the full budget.

They own nine 1-gallon jugs, but three sit on a high shelf only one adult can reach. Their ledger shows 9 gallons stored and 6 gallons reachable by everyone. Moving the three jugs to a low cupboard fixes more than buying another tank would.

1. List everyone in your household, plus pets and any special needs.
2. Calculate your 3-day and 14-day starting reserves in gallons and liters.
3. Count what you already have. Write three columns: stored now, planned, still missing.
4. Walk to where the water is (or will be) and note whether each person can reach and pour it. If a shelf or container is unsafe to reach, write that down and stop there.

Expected result: two numbers, a three-column ledger and at least one access note.

Save the calculation, the three-column ledger and your access notes. Next lesson, you decide which water sources you can trust to fill that reserve.

• CDC: Creating and Storing an Emergency Water Supply, quantities and additional needs.
• Ready.gov: Build a Kit, household supplies.