Emergency Water Storage & Purification Guide
You can last weeks without food but only days without water. This guide covers how much to store, the containers and chemicals to use, how to disinfect and filter, and how to find water near you when storage runs low.
Key takeaways
- Store at least 1 gallon per person, per day — target two months per adult.
- Food-grade 55-gallon barrels are the workhorse of home water storage.
- Calcium hypochlorite disinfects huge volumes and stores for ~10 years.
- Keep high-capacity filters on hand and know your local water sources.
How much water should you store?
The baseline is one gallon per person per day — half for drinking, half for cooking and hygiene. A two-week supply is a solid starting point; a serious target is two months per adult, or roughly 60 gallons each. For most households that means two or three 55-gallon barrels. Hot climates, pets, and medical needs push that number up.
Storage containers
Food-grade 55-gallon barrels are the standard for bulk storage: durable, stackable-adjacent, and easy to treat and rotate. Stabilize them on a level surface off bare concrete. Smaller stackable containers and commercial water boxes are great for apartments or for topping up a barrel system.
Filling and treating your water
Municipal tap water is already treated, so you can store it directly — but adding a small dose of disinfectant guards against any contamination over months of storage:
- Clean and rinse the barrel thoroughly.
- Fill with tap water.
- Treat with calcium hypochlorite (or unscented household bleach) at the recommended dose.
- Seal, label with the date, and store in a cool, dark place.
- Empty and refill every six months to keep it fresh.
Water disinfection: calcium hypochlorite
For storage, calcium hypochlorite (often sold as pool shock) beats liquid bleach in every way that matters to a prepper. A single one-pound bag can treat up to 10,000 gallons of water and has a roughly 10-year shelf life — whereas liquid bleach loses potency within months. You mix a small amount into a stock chlorine solution, then use that solution to treat your water.
Handle with care
Calcium hypochlorite is a strong oxidizer. Store it dry, away from fuels and acids, in its original container, and follow the dosing instructions exactly. Never store it next to your gasoline or stabilizers.
Water filtering
Disinfection kills pathogens; filtering removes sediment, particulates, and many contaminants — you want both. High-capacity gravity (ceramic) filters can process thousands of gallons per element, which is why preppers buy spares and store them. Compact options like the Sawyer Squeeze are perfect for a bag or vehicle. Eventually, stored commercial elements run out — knowing how to build a basic sand-and-charcoal filter is a worthwhile long-term skill.
Compare the best emergency water filters →
Know your local water sources
Storage buys you time; nearby water buys you the long term. Study satellite maps around your home and you may be surprised how close fresh water is — ponds, creeks, and streams that aren't obvious from street level. Many people find several sources within a few hundred yards. Map them now, before you need them. Any water you collect must be filtered and disinfected before drinking.
Rainwater collection is worth setting up as a supplement, but don't rely on it as your primary source — droughts are exactly when you'd need it most and exactly when it isn't falling.