Three days of no power and no tap comes down to 3 numbers per cat: 60 ml of water per kg of body weight per day, 3 days of food, and a room that stays under 30 C. For a 4 kg cat that is 240 ml a day, 720 ml for the full window, and about 180 g of dry food. Add 1 spare day of everything, because a 72-hour outage is an average, not a promise, and water is the part people get wrong.
The 60 ml/kg rule and the 72-hour total
Water need scales with weight and with what the cat eats: a cat on dry food drinks most of its water, a cat on wet food already takes in 70 to 80 percent of its moisture from the food. Plan 60 ml per kg per day as the floor, then add 100 ml per day per cat for bowl washing and a damp cloth. That gives 240 to 340 ml per day for a 4 kg cat, and 720 to 1,020 ml for 72 hours. Store 1.5 L per cat: 0.5 L for the third day as a buffer, and 1 bottle frozen in the freezer to keep the cooler cold if the fridge dies.
Food: 3 days weighed, not scooped
A 4 kg adult eats 55 to 65 g of dry food a day, so 3 days is 165 to 195 g; buy a 500 g bag and keep 200 g unopened as the floor. A 6 kg cat needs 75 to 90 g a day, 225 to 270 g for 3 days. Weigh the portion on a kitchen scale for the first week, then keep 1 measuring cup that matches your cat, because cups vary by 30 percent between brands. Store the bag at 15 to 25 C in a sealed container, write the open date on the lid, and rotate it every 6 months. After 72 hours a stress-anxious cat may refuse food for 24 hours; that is expected, but 48 hours without eating in an overweight cat is a liver risk and a clinic call.
Two temperature lines, 26 C and 30 C
A digital room thermometer at cat height, 40 cm off the floor, read every hour and written down. At 26 C start passive cooling: close the sun side, move the cat to the lowest floor, lay a damp towel on tile, and point a fan at the cat rather than at the room. At 30 C stop cooling and relocate: a car with air conditioning, a neighbor, a relative 20 minutes away. Open-mouth breathing or drooling at 30 C is a clinic call, not a cooling exercise. In winter the line is 15 C: a kitten under 6 months, a cat over 12 years, or a thin cat loses heat faster than it makes it, and a hot water bottle wrapped in 1 towel is the tool.
The supply table, by body weight
| Weight | Water per day | Water for 72 h | Dry food per day | Food for 72 h |
|---|---|---|---|---|
| 3 kg | 180-250 ml | 0.8-1.1 L | 45-55 g | 135-165 g |
| 4 kg | 240-340 ml | 0.9-1.2 L | 55-65 g | 165-195 g |
| 5 kg | 300-400 ml | 1.1-1.5 L | 65-80 g | 195-240 g |
| 6 kg | 360-470 ml | 1.3-1.8 L | 75-90 g | 225-270 g |
| 8 kg | 480-620 ml | 1.7-2.3 L | 90-110 g | 270-330 g |
Weight also sets the carrier: a cat should turn around inside it, so 1.5 times body length is the minimum, and a 6 kg cat needs a 55 cm carrier. Label the water bottles with the fill date and rotate them every 6 months. Bottles stored beside a radiator or in a car trunk taste of plastic within 8 weeks and a cat will refuse them, which is the failure mode nobody plans for.
When the tap is dry
Fill the bathtub at hour 1, before pressure drops, and cover it: 150 L lasts a 4 kg cat 400 days of drinking but only about 10 days of flushing and washing. Keep 2 buckets of 10 L for litter and cleaning, separate from drinking water. If you must use questionable water, boil 1 minute at a rolling boil, or use unscented chlorine bleach at 2 drops per liter, stir, and wait 30 minutes before offering it. Pour bottled water into a ceramic or steel bowl: a cat that normally drinks from a fountain may ignore a bowl for 12 hours, so offer 2 bowls in 2 rooms and add 2 ice cubes to the one it uses.
Litter, medicine and the first 4 hours of the fridge
No running water means no rinsing: use 2 kg of litter across 2 trays, scoop twice a day, and bag waste in a 20 L bucket with a lid. A closed fridge holds 2 to 8 C for about 4 hours, 2 hours if the door opens 5 times, so at hour 1 move insulin and any refrigerated drug into a cooler with 2 frozen packs and a thermometer, wrapped in 1 cloth, never touching ice. Unopened insulin keeps 28 days at 2 to 8 C once in use. The power outage plan covers the hour-by-hour order, and the storm prep checklist covers the 48 hours before the wind arrives, when buying 6 L of water is still easy.
Water safety and spoiled food
After a flood, assume tap water is contaminated until the utility says otherwise, and do not let the cat walk through standing water then groom itself. Throw out any dry food that touched floodwater, and any can that is dented at the seam or bulging: the risk is not mold but a toxin that survives boiling. If the cat ate something spoiled or unknown in the dark, the toxic substance lookup tells you whether 1 phone call or a drive is the right move.
People first, and never re-enter
No supply run is worth a stairwell with a 5 mm crack, a door that will not close, or a gas smell. If the building is unsafe, take the 1.5 L bottle, the carrier and the cat if it is already at the door, and go to the meeting spot 50 m out; leave the rest, call the utility, and let a rescue team with helmets make the entry in pairs within 24 hours. People first, and never go back into a damaged building for a bag of food.
5 steps this week
- Weigh the cat, multiply kg by 60, and write the daily ml on the water bottles.
- Buy 1.5 L of water per cat, 1 bag of 500 g dry food, and 2 kg of litter.
- Freeze 1 bottle per cat and put 2 ice packs in the freezer for the cooler.
- Tape a 26 C and a 30 C card beside the room thermometer at 40 cm.
- Write the fill date on every bottle and set a 6-month rotation reminder.
Terms mentioned in this article
Frequently asked
How much water does a cat need for 72 hours without a tap?
Use 60 ml per kg per day as the floor and add about 100 ml per day for washing bowls, so a 4 kg cat needs 240 to 340 ml daily and 0.9 to 1.2 L for the full window. Store 1.5 L per cat to leave a 0.5 L buffer, freeze 1 bottle for the cooler, and rotate the stock every 6 months.
How much food should I keep for 3 days?
A 4 kg adult eats 55 to 65 g of dry food a day, so 165 to 195 g covers 3 days; a 6 kg cat needs 75 to 90 g a day, or 225 to 270 g. Weigh portions rather than using cups, which vary up to 30 percent between brands, and add 1 spare day for a 500 g bag kept sealed at 15 to 25 C.
What do I do with the fridge and refrigerated medicine?
A closed fridge holds 2 to 8 C for about 4 hours, or 2 hours if the door opens 5 times, so move insulin and other cold drugs into a cooler with 2 frozen packs at hour 1. Wrap them in cloth so nothing touches ice, keep a thermometer in the box, and remember opened insulin lasts 28 days at 2 to 8 C.