How much emergency water do you need in a heat wave?
The short answer
Plan on 2 gallons per person per day instead of 1. Ready.gov says that in very hot temperatures, water needs can double. If you live somewhere hot, or you're planning for a summer power outage, store for the heat. Then drink what you need, even before you feel thirsty.
Your water, with and without the heat
| Household | 3 days | 3 days, very hot | 2 weeks | 2 weeks, very hot |
|---|---|---|---|---|
| 1 person | 3 | 6 | 14 | 28 |
| 2 people | 6 | 12 | 28 | 56 |
| 4 people | 12 | 24 | 56 | 112 |
These numbers are for people only. Pets need more in the heat too. The water storage calculator opens here with very hot weather already turned on, so you can add your own household and pets.
Who needs extra
Ready.gov says children, nursing mothers and people who are sick may need more water. The CDC adds pregnant women and pets, and says to store more if you live in a hot climate. Older adults, children and people with chronic conditions are also at greater risk from extreme heat, so plan generously for them.
Drink before you're thirsty
- Don't wait. The CDC says to drink plenty of fluids even if you don't feel thirsty.
- Pick the right drinks. The National Weather Service says water and non-alcoholic, decaffeinated drinks. For children, fluids shouldn't be very cold or very sugary.
- Don't ration. Ready.gov says never to ration drinking water unless the authorities tell you to. Drink what you need today and look for more tomorrow.
- Check with a doctor first if someone in your home has been told to limit fluids.
Know the warning signs
| Condition | Signs | What to do |
|---|---|---|
| Heat exhaustion | Heavy sweating, paleness, muscle cramps, tiredness, weakness, fast or weak pulse, dizziness, headache, fainting, nausea, vomiting | Move somewhere cooler and take sips of water or a sports drink |
| Heat stroke | Body temperature above 103°F, red, hot and dry skin with no sweat, rapid strong pulse, dizziness, confusion or unconsciousness | Call 911 or get the person to a hospital right away |
Keep the water itself cool
The CDC says to keep stored water between 50 and 70°F and out of direct sunlight. In a heat wave, that rules out a hot garage, an attic or a car. Keep most of your supply inside the coolest part of your home. Our guide to storing water in a garage or car explains why.
Never leave anyone in a parked car
Ready.gov says never to leave people or pets in a closed car on a warm day. The National Weather Service warns that cracking the windows doesn't slow the heat down much, and that a parked car can turn dangerous even when it's in the 70s outside.
Get your number
Use the water storage calculator with very hot weather turned on. It adds people, days and pets, then tells you how many containers you need, how much they weigh and when to replace them. Pets have their own water guide.