Food safety in a power outage: 4 hours for the fridge, 48 for a full freezer

Storms, heat waves and earthquakes all knock out power, and the first question is usually the same: is the food in the fridge still safe? U.S. and Japanese agencies give nearly identical numbers, with one interesting difference on refreezing.

Before the outage: the normal settings

The U.S. settings are stricter, and an appliance thermometer is the only way to know the actual temperature, during an outage or not.

How long food stays cold, door closed

Both say to keep the doors closed as much as possible. Japan's ministry adds that these are rough guides that change with room temperature and how much food is inside; the U.S. figures show the same thing, since a full freezer lasts twice as long as a half-full one.

What to throw away

• FoodSafety.gov: discard refrigerated perishable food such as meat, poultry, fish, eggs and leftovers after 4 hours without power.
• Japan's MAFF: throw out perishable meat, fish and prepared dishes once they pass the time guide, and don't eat chilled or frozen foods that couldn't be kept at the right temperature.
• FoodSafety.gov: after a power outage, never taste food to determine its safety. When in doubt, throw it out.

Refreezing: the two countries differ

FoodSafety.gov says food may be safely refrozen if it still contains ice crystals or is at 40°F (4°C) or below, though its quality may suffer. Japan's MAFF simply says to avoid refreezing frozen food that has completely thawed. The two are compatible (fully thawed food has no ice crystals left), but the Japanese wording is more cautious. When unsure, don't refreeze.

Why the 2-hour rule still matters

Separate from the 4-hour fridge window, FoodSafety.gov's everyday rule is to never leave perishable food out of refrigeration for more than 2 hours, or 1 hour above 90°F (32°C), because bacteria multiply fastest between 40°F and 140°F. During a summer outage, food you take out to cook or serve is on that clock too.

Prepare before the next outage (our suggestions)

• Keep appliance thermometers in the fridge and freezer.
• Keep frozen water bottles or ice packs in the freezer: they fill empty space so the freezer holds the cold longer, can move to the fridge or a cooler, and become drinking water.
• Know where you'd get ice, and have a cooler ready for longer outages.
• Eat from the fridge first, then the freezer, then your shelf-stable rolling stock.