Water is the resource that decides whether a shelter is survivable. You can improvise almost everything else, but you cannot improvise the three-to-four days it takes to die of dehydration. This is the guide to getting water right — how much to store, how to keep it safe, and how to make more when your stores run down.
How much water you actually need
The standard planning figure is one gallon per person per day: roughly half for drinking and half for cooking and basic hygiene. That is a survival minimum, not a comfortable one. Add more if you have children, anyone with medical needs, pets, or a hot climate.
Run the math for your own situation. A family of four planning for 90 days needs about 360 gallons just to hit the minimum — and realistically closer to 500-plus for any comfort. Use the Planning Calculator to turn your headcount and duration into a real target, then design storage to match in the Builder.
Store it in layers
No single container solves water storage. The best setups layer three tiers:
- Bulk tanks for the backbone of your supply. Stackable options like the WaterPrepared 55-Gallon Stackable Tank pack hundreds of gallons into a small footprint, while a Norwesco Vertical Water Storage Tank scales into the hundreds of gallons if you have the room.
- Portable containers you can actually carry and pour. Rugged Reliance Aqua-Tainer 7-Gallon jugs and modular WaterBrick 3.5-Gallon Stackable Containers fit into odd corners and move easily.
- Last-minute capacity for when you see a crisis coming. A WaterBOB Bathtub Storage (100 gal) turns an ordinary bathtub into 100 gallons of clean water in minutes.
Keep stored water safe
Clean water sealed in a food-grade container is stable for a long time, but it is not truly "forever." Light and warmth encourage algae and biofilm, so store containers in the dark and cool if you can. Treating each container with a product like Water Preserver Concentrate (5-yr) can extend safe storage up to five years and cut down on rotation chores. If you use barrels, keep a Drum Bung Wrench on hand — you cannot open a sealed drum without one.
Filtration vs. purification — know the difference
These two words are not interchangeable, and confusing them gets people sick:
- Filtration physically strains out sediment, bacteria, and protozoa. Most gravity and pump filters do this well.
- Purification goes further and inactivates viruses, which are small enough to slip through many filters. Chemical treatments like Aquamira Water Treatment Drops or a purpose-built purifier handle viruses.
For a shelter, the safe approach is a good filter for everyday use plus a chemical purifier as a virus backstop. Our gravity vs. pump filtration guide breaks down which system fits your needs.
Have a way to make more
Storage is finite; a renewable source is not. Two additions turn a fixed supply into a sustainable one: a filtration system that lets you safely use nearby water, and a rainwater collection setup that captures water from the sky. Together they mean your countdown clock resets every time it rains.
Test before you trust
When you tap a new source — a stream, a well, collected rain — a two-minute water test tells you whether it is safe or needs heavier treatment. In close quarters, a preventable waterborne illness spreads fast. Testing is the cheapest insurance you can buy.