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If the power goes out across a wide area and phones, the internet and some cars stop working at the same moment, the first three days will be decided by ordinary things: water, information, food safety, heat or cooling, medicine and getting your household together. This plan puts those in order. It draws on federal power-outage guidance, the government’s EMP protection guidelines and the federal EMP Commission’s report, which actually tested how vehicles respond to EMP. It doesn’t rely on the collapse scenarios that fill most EMP articles.
Short version: stay where you are unless you are in danger. Listen to a battery radio for official information. Unplug appliances, keep the fridge and freezer closed and secure drinking water early. Use only safe heat and light, check who needs medicine or powered equipment, and follow the family plan you made in advance. Most of these steps are the same as for any long blackout, which is useful, because at first you may not know which one you are in.
How would you know it’s an EMP?
You might not, at least not right away. A high-altitude EMP and a large grid failure can look alike for the first hours: no power, no internet and no phone service. The differences are less obvious than many guides suggest:
- Cars: in the EMP Commission’s tests, most running cars kept going or restarted, so traffic on the road doesn’t rule an EMP out (details in our guide to the most dangerous places in an EMP).
- Small electronics: the federal EMP Protection and Resilience Guidelines say small devices without cables, such as phones and handheld radios, are relatively resilient. Their networks are not, so a phone that turns on but has no signal is consistent with either cause.
- A flash or blast nearby is different. It means a nuclear detonation close to you, and the priority becomes radiation protection: get inside, stay inside and stay tuned. Follow our nuclear emergency steps instead of this page.
The practical answer: treat it as a major, possibly long outage from the first minute. Nothing on this list is wasted if power comes back that evening.
The first hour
- Get yourself safe where you are. If you are driving and the engine dies, use your hazard lights if they work, steer to the shoulder and try a restart. Treat dark or erratic traffic signals with great caution. If you are stuck in an elevator, use the alarm and wait for trained rescuers; don’t climb out.
- Turn on a battery radio. The federal EMP guidelines say battery-operated AM/FM/NOAA radios are “relatively resilient to EMP.” They add that Emergency Alert System stations have some protection, and handheld or car radios may be the main way to hear what officials want you to do. Our hand-crank emergency radio guide compares models with NOAA weather band and several power options.
- Unplug appliances and electronics. Ready.gov’s power outage guidance warns that power may come back with surges that damage equipment. Leave one lamp switched on so you notice when it returns.
- Keep the fridge and freezer closed. A closed refrigerator keeps food cold for about four hours, and a full freezer holds its temperature for about 48 hours.
- Save your phone battery. Switch to low-power mode and check for signal now and then rather than continuously.
- Stay put unless you are in danger. Walking out of a city on the first afternoon, as some EMP articles urge, swaps a home with water, food and shelter for an open road with none of them. Leave only for a real hazard, such as fire, extreme heat or cold you can’t manage, or an official evacuation.
The first day
Water first
Water treatment and pumping depend on electricity. The EMP Commission noted that backup generators at sites like water systems usually carry less than 72 hours of fuel. If your tap still runs, fill clean containers for drinking and cooking while pressure lasts. Then rely on what you have stored. The CDC baseline is at least one gallon per person per day. Our emergency water calculator turns that into gallons, weight and a container count for your household. If you need containers for next time, see stackable water storage containers on Amazon.
Food: eat in the right order
Eat perishable food first, then what’s in the freezer, then shelf-stable food. Ready.gov’s rule for anything that has been above 40°F for two hours or more, or that smells, looks or feels wrong, is: “When in doubt, throw it out!” Our emergency food supply calculator shows how long your pantry would last.
Medicine and medical equipment
This is the most time-critical step for many households. Ready.gov says refrigerated medication should be thrown out if the power has been out for more than a day, unless the label says otherwise, and that you should ask your doctor or pharmacist for a new supply. Anyone who depends on powered equipment, such as an oxygen concentrator, needs the backup plan made with their provider. If that plan runs out, they need to go early to a place that has power.
Safe heat, cooling and light
- Never heat your home with a gas stove or oven.
- Run any generator outdoors only, at least 20 feet from windows, doors and attached garages.
- Carbon monoxide is odorless and kills. Ready.gov recommends battery-backup carbon monoxide detectors on every level of the home. If yours are wired to the mains with no battery, see battery-operated CO detectors on Amazon.
- Use flashlights and lanterns rather than candles, with one light for every household member. Our survival flashlight guide explains how to choose by battery type.
- If heat or cold becomes dangerous, Ready.gov’s advice is to go to a community location with power. Listen for warming or cooling centers on the radio.
Bring the household together, by plan
With phones down, the plan you agreed in advance is what reunites people. Decide who collects the children from school, where you meet if home is unsafe, and which out-of-area contact everyone tries to reach when calls start getting through. Keep it on paper. Our printable emergency contact card fits in a wallet. If someone is far from home, a predictable plan (stay at work tonight, walk home tomorrow by a known route) is safer than everyone setting out to look for each other.
Days 2 and 3
Settle into a routine
By the second day you are managing a long outage. Keep listening to the radio at set times. Track your water and food against the calculator plan, and keep the freezer closed until you are ready to cook from it. Our household power-outage planner builds a day-by-day checklist for your home. If you live in an apartment, our apartment outage plan covers stairs, water and shared spaces.
Fuel and travel
The EMP Commission concluded that once the first traffic jams clear, travel will be limited mainly by fuel and electric power: “service stations need electricity to power pumps,” and few have backup generators. Don’t plan on refueling. Use the fuel you have for essential trips only, and keep it for a medical journey or a move you actually need to make.
Neighbors and public order
Most EMP fiction predicts rioting hordes within hours. The historical record the commission cites is mixed. During the 1965 Northeast blackout, it notes “few instances of antisocial behavior while the lights were out”. In New York’s 1977 blackout, blocks were looted and set on fire until power was restored. Disorder is possible, but it isn’t automatic, and neighbors are usually your nearest help. Sensible precautions:
- Check on older and medically vulnerable neighbors.
- Share radio updates.
- Pool resources such as a working generator or extra water.
- Keep supplies out of sight and doors locked.
Your electronics
If you stored spare radios, a phone or a battery bank in a Faraday bag or foil wrap, take them out once you need them. Keep them unplugged from long cords until power is stable. Our guide to protecting electronics from an EMP explains what federal guidance says about storage. Our guide to communications after an EMP covers which radios are worth trying to reach family.
Three-day checklist
For a broader overview of what a large EMP could affect, see what an EMP attack is.
Why this page changed
Earlier versions of this page predicted that most of the population would die and that nuclear plants would melt down. They also claimed airliners would fall from the sky and that few cars would start, and they told readers to abandon their homes on foot within minutes. It also carried political and religious commentary that had nothing to do with staying safe. None of those predictions was supported by the evidence we could find. Leaving home by default contradicts official guidance for both outages and nuclear emergencies, so we replaced the page with the plan above.
The first 72 hours after a disaster are the most critical for survival. Enter your email below to get a checklist of essential items you need in your 72 hour emergency get home bag…
How we researched this guide
Research method: This is a research-led summary of official guidance and published evidence. It is not personal experience, testing or expert certification. The household steps come from Ready.gov’s Power Outages page (updated June 4, 2026) and its Radiation Emergencies page (updated January 7, 2025). Radio guidance comes from the CISA-hosted EMP Protection and Resilience Guidelines (version 2.2, 2019). Vehicle, fuel, generator and blackout-history findings come from the EMP Commission’s 2008 critical infrastructure report. We checked all of them on November 7 and 8, 2026. We deliberately left out casualty estimates and any judgment of how likely an EMP attack is. Follow local officials if their instructions differ from this page.
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The first 72 hours after a disaster are the most critical for survival. Enter your email below to get a checklist of essential items you need in your 72 hour emergency get home bag…
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