Prep Guide
How to Build an EMP Survival Kit
An electromagnetic pulse (EMP) — from a severe solar storm or a high-altitude nuclear detonation — could damage the power grid and some electronics across a wide area at the same moment. Nobody can say exactly which devices would fail; tests over the decades have given mixed results. That uncertainty is the point of an EMP survival kit: build a kit that keeps your household going whether your phone, car and appliances work or not. The good news is that most of what protects you from an EMP is the same gear that protects you from any long blackout.
This is for educational purposes only. Not professional medical, electrical, or safety advice.
What an EMP would actually change
The most likely and most serious effect is on the grid itself. Large transformers are hard to replace, so power could be out for weeks or longer over a whole region. Without power, municipal water pumps, fuel pumps, card readers, cell towers and refrigeration stop too. Smaller electronics may or may not survive, depending on their design and whether they were plugged in.
Plan for the worst version — no grid, no reliable phones, no electronic payments — and treat anything that still works as a bonus. That mindset keeps you from spending money on gadgets and pushes you toward water, food, heat and skills, which work regardless.
The core of an EMP survival kit
Start with what keeps people alive, in this order. None of these need a working circuit board:
- Water: at least 1 gallon per person per day, and a way to treat more — unscented bleach, a gravity filter and a pot to boil in.
- Food: two weeks or more of shelf-stable food that needs little or no cooking, plus a manual can opener.
- Heat and cooking: warm layers, sleeping bags and an outdoor-only cooking method such as a rocket stove. Never burn fuel indoors.
- Light: flashlights and headlamps with spare batteries, stored in protective containers (see below).
- First aid: a stocked kit and at least a two-week supply of prescription medicines where your pharmacist and insurer allow.
- Cash in small bills and paper copies of key documents, since card networks will be down.
Protecting electronics with Faraday storage
A Faraday container is a closed metal box that shields what's inside. A galvanized steel trash can with a tight lid, a metal ammo can, or several layers of heavy-duty foil wrapped with no gaps are common home options. Line the inside with cardboard or foam so the item doesn't touch the metal, and keep the seal tight — a gap undoes the shielding.
Good candidates for storage: a spare battery or crank radio, a small solar charger, a backup flashlight, an old phone loaded with offline maps and documents, and spare batteries. A simple test is to put a phone inside and call it; if it rings, the container leaks. That test only checks radio signals, not a real EMP, so treat it as a minimum check rather than proof.
Communication when phones are down
Assume cell and internet service will be gone. A battery or hand-crank AM/FM/NOAA weather radio lets you hear official broadcasts if any stations are back on air. Agree a meeting place and an out-of-area contact with your family in advance, and write key phone numbers on paper. Know your neighbors — in a regional outage, the people on your street are your fastest source of help and information.
Power you can rebuild
A small solar panel and battery bank, stored disconnected and shielded, can recharge lights, radios and a phone after the event. Keep expectations realistic: small systems run small loads. Running a fridge or well pump takes a properly sized system and safe wiring — size it before you buy.
Practice the no-power plan
Kits fail when nobody knows how to use them. Spend a weekend with the main breaker off: cook outside, treat water, light the house with your kit. You'll find the gaps fast — usually water volume, lighting and keeping one room warm or cool. Fix those first, then add the extras.
Go deeper with Gridfall field guides
- Off-Grid Communication — Radios, signals and family check-in plans.
- Build a Bucket Gravity Water Filter — Clear water before you disinfect it. Free guide.
- Solar Battery Bank — Rebuild small-scale power after the grid fails.
- Store Water Safely Long-Term — How much water to keep and how.
- Rocket Stove — Outdoor cooking with little fuel.
- Gridfall Survival — Lifetime Access ($79) — Every field guide, the offline manual and the AI advisor, one payment.
Free download
The 72-Hour Grid-Down Checklist
One printable page: water, food, power, communication, first aid, security and documents.
Frequently asked questions
What should be in an EMP survival kit?
Water and a way to treat it, two or more weeks of shelf-stable food, warm layers, an outdoor cooking method, flashlights and batteries, a first-aid kit and medicines, cash, paper documents, and a radio and small solar charger stored in a Faraday container.
Does a Faraday cage really work?
A fully closed metal container shields radio-frequency energy, and the same principle applies to an EMP. Gaps and poor seals reduce protection. Insulate items from the metal and keep the lid tight. A phone-call test checks for leaks but is not proof against a real EMP.
Will my car work after an EMP?
Nobody knows for certain. Government tests showed some vehicles stalled and most restarted, but results vary by vehicle. Plan to move on foot or by bicycle, and keep fuel stored safely in case your vehicle runs.
How long should an EMP kit last?
Aim for at least two weeks for water, food and medicine, then build toward longer. A grid-scale EMP could mean a regional outage lasting weeks or months, so skills like water treatment and food preservation matter as much as stored supplies.