Free Tool · Water Preparedness

Emergency Water Storage Calculator

Work out a practical emergency-water target for your household, see how much you still need to store, and get an idea of the space and weight involved.

Official baseline: CDC guidance says to store at least 1 gallon per person per day for 3 days and, if possible, work toward a 2-week supply. CDC also says to consider extra water for pets and certain circumstances. This calculator uses that 1-gallon baseline and keeps any extra allowance clearly separate.

1. Household

People in household Days to prepare for

2. Pets & animals

Pets / animals Planning allowance per animal/day (gal)Set this yourself for the animal(s) you keep. CDC says to include pets; species-specific livestock needs vary widely.

3. Conditions & extra use

Planning buffer Optional planning buffer for circumstances such as heat, higher activity or special household needs. CDC advises storing more in hot climates and for some people, but does not prescribe these percentage multipliers. Extra household water/day (gal)Optional cooking, cleaning, hygiene or other reserve above the baseline.

4. Water you already have

Stored bottled / container water (gal) Usable water-heater reserve (gal)Only count water you reasonably expect to be accessible and safe in your situation. Other dependable reserve (gal)For example, another stored potable-water source. Do not count an untreated source as safe drinking water.

Total planning target28 gallons106 liters

Your emergency-water gap28 gallonsafter counting the reserves entered above

CDC people baseline28 gal

Animal allowance0 gal

Extra + buffer0 gal

Existing reserves0 gal

Total water weight234 lb

Approx. metric weight106 kg

Ways to cover the remaining gap

These are capacity equivalents for the remaining gap, not a recommendation to use one container type exclusively. Smaller containers are easier to move and rotate.

Visible calculation

How the calculator works

The calculator starts with the CDC baseline of 1 gallon per person per day. It then adds the animal allowance and any extra daily water you enter, applies your optional planning buffer, and subtracts the water reserves you say are already available. The result is your estimated emergency-water gap.

Important: This is a planning tool, not individualized medical or public-health advice. Water needs vary with climate, activity, pregnancy, illness and other circumstances. Follow instructions from local authorities during an emergency.

Why 3 days and 14 days matter

The CDC recommends storing at least a 3-day supply and says to try for a 2-week supply if possible. That makes 3 days a sensible minimum planning point and 14 days a useful longer-term target.

Storage basics

CDC guidance says commercially bottled water is the safest and most reliable emergency source. If you fill your own containers, use food-grade water-storage containers, keep them tightly closed, and do not reuse containers that previously held toxic chemicals. CDC says self-filled stored water should be replaced every six months.

Build the rest of your water plan

A number on a calculator is only the first step. Use the guides below to decide how to store it and what your backup plan looks like if the taps stop running.

Emergency water storage guide Build a backup water supply

Sources

This calculator's baseline and storage guidance are based on current CDC emergency-water guidance and Ready.gov preparedness guidance. Source links are provided for checking the underlying recommendations directly.