Water Needs: How Much Water Your Household Really Needs

By GoldBlock WorkshopPublished Updated

The short answer

Store at least one gallon of water per person per day for drinking and sanitation: at least 3 days’ worth, and 2 weeks at home if you can. Store more for hot weather, pregnancy, nursing, illness and children, add water for cooking dry food, and count every pet and animal. Work out your household’s number once, then build your supply to it.

Key numbers

  • 1 gallonwater per person per day to store, for drinking and sanitationSource: Ready.gov
  • About ¾ gallonfluid a normally active person needs daily, from water and other drinksSource: Ready.gov
  • 14 gallonsone person for 2 weeks at 1 gallon a day: 1 × 14 × 1 = 14Source: CDC and Red Cross figures
  • Can doublewater needs in very hot temperaturesSource: Ready.gov

How much water does a person need per day?

Plan on one gallon per person per day. Ready.gov’s advice is to store “at least one gallon of water per person per day for several days, for drinking and sanitation,” and the CDC and the American Red Cross use the same gallon.

That gallon is more than a person drinks. Ready.gov notes that “a normally active person needs about three quarters of a gallon of fluid daily, from water and other beverages.” The rest covers basic sanitation, such as washing hands and brushing teeth. The sources name who needs more: Ready.gov says needs “can double” in very hot temperatures and that “Children, nursing mothers and sick people may need more water”; the CDC says to store more “for pregnant women, people who are sick, pets, or if you live in a hot climate.”

Two things the gallon does not cover well:

  • Cooking dry food. Freeze-dried and dehydrated meals need water on top of drinking water. The emergency food kits we compared list from about 7 to about 21 gallons just to prepare their meals; see Storable Emergency Food Compared.
  • More than basic hygiene. Dishes, laundry, bathing and flushing a toilet by hand use far more than a gallon; Ready.gov’s gallon is “for drinking and sanitation,” and the CDC says its stored water is “for drinking, cooking, brushing teeth, and other uses.” The CDC says water from swimming pools and spas “can be used for personal hygiene, cleaning, and related uses, but not for drinking” (CDC: How to Find Clean Water in an Emergency), which is the same principle as flushing with water you would not drink. For washing dishes and bathing while your water is under an advisory, follow your utility’s instructions and the CDC’s advisory guidance.

How many days of water should I store?

Store at least 3 days of water for each person, and 2 weeks at home if you can. The CDC says to store water “for 3 days” and to “try to store a 2-week supply if possible.” The American Red Cross gives the clearest split: a “3-day supply for evacuation, 2-week supply for home.” Ready.gov says “several days.”

The household math is people × days × gallons per day.

Household 3 days (evacuation) 2 weeks (at home)
1 person 3 gallons 14 gallons
2 people 6 gallons 28 gallons
4 people 12 gallons 56 gallons
6 people 18 gallons 84 gallons

These totals are the floor at one gallon per person per day. Add for heat, the people listed in the next section, cooking and animals. The CDC says that without bottled water you should make other water safe using its guidance, so the stored supply works alongside a treatment method; see Making Water Safe to Drink.

Who needs more water?

Some people and conditions need more than the gallon, so store extra for them.

  • Hot weather. “In very hot temperatures, water needs can double” (Ready.gov). Hard physical work, such as hauling water or clearing storm damage, raises needs too; the CDC lists higher physical activity, hot climates, fever, and diarrhea or vomiting as times the body needs more water (CDC: About Water and Healthier Drinks).
  • Pregnancy, illness and children. The CDC advises storing more “for pregnant women, people who are sick, pets, or if you live in a hot climate.” Ready.gov adds: “Children, nursing mothers and sick people may need more water.”
  • Medical needs. Ready.gov: “A medical emergency might require additional water.” Anyone who depends on water for care at home should plan that water with their care team.

How do babies change the plan?

In the CDC’s words, “ready-to-feed (RTF) infant formula is the safest option.” For powdered formula, the CDC advises: “Use bottled water to prepare powdered formula until local authorities say the tap water is safe to drink.”

Keep a supply of ready-to-feed formula in your stores if your baby uses formula, and count bottled water for any powdered formula on top of the household’s gallon a day; in an emergency the CDC says “ready-to-feed (RTF) infant formula is the safest option” and to “Use bottled water to prepare powdered formula until local authorities say the tap water is safe to drink” (CDC: Prepare and Store Powdered Infant Formula in an Emergency).

How much water do pets and animals need?

Count every animal: a dog over 50 pounds needs “upwards of 10 cups” a day (more than half a gallon; a gallon is 16 cups), twenty-five hens can drink about a gallon, and a horse 10 to 12 gallons (sources below). The figures are typical daily amounts from veterinary and extension sources. The University of Maine notes that lactating cows need more, “up to 8 gallons or more on hot, dry days and much more when grazing on dry forage,” and that livestock “can get the majority of their water by grazing on lush forage that is 70 to 90% water.”

Animal Typical water per day Source
Cat About 1 cup Texas A&M veterinary school
Dog under 50 lb Up to 5 cups Texas A&M veterinary school
Dog over 50 lb Upwards of 10 cups Texas A&M veterinary school
Laying hens “Twenty-five hens can drink a gallon of water each day” University of Florida extension
Sheep, goats, llamas 2 to 4 gallons each University of Maine extension
Hogs 4 gallons each University of Maine extension
Horses 10 to 12 gallons each University of Maine extension
Beef cattle, dry dairy cows 12 to 15 gallons each University of Maine extension
Milking dairy cows About 40 gallons each University of Maine extension

The University of Florida’s extension adds: “Water consumption will increase dramatically during hot weather.” At 12 to 15 gallons a head, two beef cattle for two weeks need 336 to 420 gallons (2 × 14 × 12 = 336; 2 × 14 × 15 = 420); a well pump stops when its power does (Backup Power for Vital Loads). Ask your veterinarian about any animal that is nursing, ill or very young.

What are the signs of not drinking enough?

The Arizona Department of Health Services’ hydration chart says: “If your urine is pale and has little to no smell, it usually means you’re hydrated”; “Medium to dark yellow urine often indicates dehydration”; and “Dark, strong-smelling urine in small amounts is a sign of severe dehydration” (Arizona Heat Preparedness Network: Urine Chart Guide to Hydration, read October 19, 2026).

NIOSH lists heat exhaustion symptoms including headache, nausea, dizziness, weakness, irritability, thirst, heavy sweating, elevated body temperature and decreased urine output.

What can and cannot stretch a water supply?

Ready.gov is direct: “Never ration drinking water unless ordered to do so by authorities. Drink the amount you need today and try to find more for tomorrow. Minimize the amount of water your body needs by reducing activity and staying cool.”

What the sources say does help:

  • The CDC reserves non-drinking sources such as pools and spas “for personal hygiene, cleaning, and related uses, but not for drinking.”
  • Ready.gov: “In very hot temperatures, water needs can double”; its advice is to minimize what the body needs “by reducing activity and staying cool.”
  • Stored foods that need little or no added water, or water planned for the ones that do (Short-Term Food Supply).
  • A way to make other water safe, so the stored supply is a bridge, not the whole plan (Making Water Safe to Drink).

Common misunderstandings about water needs

Each of these runs against a published source.

  • “Coffee and soda don’t count.” Two authoritative sources differ. The National Academies’ 2004 report summary counts all beverages toward total water and says “caffeinated beverages can contribute as much as noncaffeinated options” (National Academies, 2004). Ready.gov’s emergency page (read October 19, 2026) says “Caffeinated drinks and alcohol dehydrate the body which increases the need for drinking water” and “Do not drink carbonated or caffeinated beverages instead of drinking water.” Both agree on the planning point: the stored supply is drinking water.
  • “A case of bottled water is enough.” A common case of 24 bottles of 16.9 ounces holds about 3.2 gallons, while one person needs 14 gallons for two weeks at the floor (24 × 16.9 oz = 405.6 oz; 405.6 ÷ 128 = 3.2 gallons).
  • “Animals can fend for themselves.” The University of Maine extension figures above run from 2 to 4 gallons a head for sheep and goats to 40 gallons for a milking cow; a well pump stops when its power does (see Backup Power for Vital Loads).
  • “Rationing makes water last.” Ready.gov: “Never ration drinking water unless ordered to do so by authorities.”

Common questions

How much water should I store for a family of four?

At least 12 gallons for 3 days and 56 gallons for 2 weeks, at one gallon per person per day (4 × 3 × 1 = 12; 4 × 14 × 1 = 56; CDC and Red Cross figures). Add more for heat, pregnancy, nursing, illness, children, cooking and pets.

Does the gallon a day include cooking?

It covers drinking and basic sanitation. Dry and freeze-dried food need extra water to prepare, so add that to the total.

How much water should I store for my dog?

Texas A&M’s veterinary school says dogs under 50 pounds take in up to 5 cups a day and larger dogs upwards of 10 cups, more in heat or with exercise. A gallon is 16 cups, so 10 cups is more than half a gallon a day.

How long can a person go without water?

None of the planning sources gives a number of days to plan around. Ready.gov’s rule is to “Never ration drinking water unless ordered to do so by authorities.”

Where do I put all this water?

That is the next step: Storing Water at Home covers containers, space, rotation and the water already in your house.

Where to go next

Sources