How Much Water to Store for a Hurricane, and How to Store It

Municipal water is the utility people assume will keep working, and it is frequently the one that fails first. Water treatment plants run on electricity. When the grid goes down and generators run out of fuel, pressure drops, contamination enters the lines, and a boil-water notice follows — except you may not have a working stove to boil with.

The math

The standard federal guidance is one gallon per person per day, for a minimum of three days. That number is the survival floor for drinking and minimal sanitation. It assumes a temperate climate and no exertion. Post-hurricane conditions in the Gulf and Southeast are neither.

A more realistic target:

• Drinking: 1 gallon per person per day in heat and humidity without air conditioning.
• Cooking and hygiene: another 0.5 to 1 gallon per person per day.
• Pets: roughly 1 ounce per pound of body weight per day. A 60-pound dog needs about half a gallon.
• Duration: plan for 7 days, not 3. After a major hurricane, water service restoration is commonly measured in weeks.

For a family of four with a dog, seven days works out to roughly 60 gallons. That sounds like a lot until you realize it is twelve five-gallon jugs, which fits in a closet.

What to store it in

Commercially bottled water is the simplest option. It arrives sealed and sanitized, and unopened bottles stored in a cool dark place stay safe well past the printed date, which is a quality date rather than a safety date. Keep it off concrete floors and out of sunlight.

Five to seven gallon rigid containers made of food-grade HDPE are the best value for bulk storage. A seven-gallon jug weighs about 58 pounds when full, which is at the limit of what most people can carry comfortably — five-gallon containers are easier to handle.

Bathtub bladders are inexpensive plastic liners that hold 60 to 100 gallons in a standard tub. Fill one when a storm is 48 hours out. This water is for flushing, washing, and cleaning; treat it before drinking.

Your water heater already holds 40 to 80 gallons of potable water. Turn off the power or gas to it and shut the cold inlet valve when a boil notice is issued, then drain from the bottom valve as needed.

Do not reuse milk jugs. Residual proteins and sugars are impossible to remove fully and will grow bacteria. Two-liter soda bottles, thoroughly cleaned, are acceptable.

Rotation

Water does not spoil, but its container can degrade and its taste will flatten. Replace tap water you have stored yourself every six months. A useful habit: refill at the start and midpoint of hurricane season. Label every container with the date it was filled.

Treating water when you run out

If the stored supply runs low, you need a way to make questionable water safe. Have at least two of these:

• Boiling. A rolling boil for one minute (three minutes above 6,500 feet) kills bacteria, viruses, and protozoa. It does not remove chemical contamination. Requires a heat source that is not your electric stove.
• Unscented household bleach. Standard 6% or 8.25% sodium hypochlorite with no added scent, dye, or cleaners. Use roughly 8 drops of 6% bleach per gallon of clear water, stir, and let it stand 30 minutes. The water should have a slight chlorine smell afterward; if it does not, repeat once. Bleach loses strength — replace the bottle annually.
• Purification tablets. Chlorine dioxide tablets are compact, shelf-stable for years, and handle protozoa that plain chlorine struggles with. Follow the package contact time, which can be up to four hours for cryptosporidium.
• A pump or gravity filter. A filter rated to 0.2 microns or finer removes bacteria and protozoa. Most do not remove viruses, so pair filtration with chemical treatment when the source is questionable.

Cloudy water should be pre-filtered through a coffee filter or clean cloth and allowed to settle before chemical treatment, because suspended solids protect pathogens from disinfectant.

Water sources to avoid after a storm

Floodwater after a hurricane routinely carries sewage, agricultural runoff, fuel, and industrial chemicals. No amount of boiling or bleach makes it safe, because the contamination is chemical as well as biological. The same applies to water from a flooded well until it has been shock-chlorinated and tested. Contact your county health department for well testing after any flood event.

The 48-hour fill

When a storm enters your forecast window, before landfall:

• Fill every bathtub, using a bladder if you have one
• Fill pots, pitchers, and food-grade containers
• Run the ice maker and bag the ice into the freezer — it doubles as cold storage for food and melts into drinking water
• Run the dishwasher and laundry so you start the outage with everything clean

Water is the heaviest, bulkiest, and most-forgotten part of a preparedness kit, and it is the one you cannot improvise around. Work through the rest of your supplies with our free hurricane checklist.