Water
Three actions cover most situations: store 1 gallon (3.8 liters) of water per person per day for 3 days (12 gallons (45 liters) for a family of four), learn two purification methods, then walk to the three nearest natural water sources so you know what's around you.
→ Where to start (5-minute checklist) or jump to Storage · Boiling · Filtration
What this hub covers: the what and how across all three layers — sourcing, purification, storage. For step-by-step procedures (boiling times, bleach ratios, well drilling), follow the linked child pages. Greywater management lives at greywater; rainwater capture legality is governed by your state code, not addressed here.
Start here if you're an apartment renter: focus on Storage first — see apartment water storage for floor-load math and lease-friendly placement. Stack 5-gallon jugs under beds and in closets. Skip rainwater capture (you don't control the roof) and skip wells.
Start here if you're a family preparing for two weeks: combine Storage + Purification + a clear plan for containers, rotation, and water testing. 112 gallons (424 liters) is the target for four people × 14 days — fits in one row along a garage wall.
Start here if you own off-grid property: the work is permanent infrastructure. Read well drilling and/or spring development, plan a cistern system with first-flush diverters, and design gravity-fed distribution to eliminate pump dependency. Layer in whole-house filtration and greywater for full independence.
Municipal water treatment depends on electricity, intact pipes, and chemical supply chains. When any of those break — and in every major disaster, at least one does — your taps stop delivering safe water within hours. Flooding contaminates wells. Power outages shut down treatment plants.
Earthquakes rupture mains. A winter storm can freeze residential pipes for a week.
How much you actually need
The minimum is 1 gallon (3.8 liters) per person per day — enough for drinking and minimal cooking, per FEMA Ready.gov. A realistic target is 2 gallons (7.6 liters) per person per day, which covers hygiene and dishwashing. For a household of four preparing for two weeks, that's 112 gallons (424 liters). It sounds like a lot, but it fits in a single row of 7-gallon containers along a garage wall.
Dehydration kills faster than hunger
Healthy adults can survive about 3 days without water before kidney function declines significantly; in heat or with physical exertion that timeline compresses to 24–48 hours (per CDC and clinical references from the American College of Emergency Physicians). Infants, elderly adults, and anyone with chronic illness or who is immunocompromised lose tolerance faster — plan their water needs as a higher priority. Water is not a supply you can skip and compensate for later.
Find water (sourcing)
Knowing where water exists near you — before you need it — is the foundation of any water plan. Every location has options whether you're urban, suburban, or rural. Start with a sourcing overview to map your options, then dig into specifics: rooftop rainwater collection — catchment math, first-flush diversion, food-safe storage; nearby springs — spring-box construction and flow measurement; or surface water — streams, lakes, ponds with multi-stage treatment. Atmospheric methods — solar stills, dew collection, and condensation traps — work when nothing else does. In winter, harvesting ice and snow — melt-and-treat fuel requirements — is an underrated option. If you own property, a well is the most reliable long-term source — and well drilling covers the full process from method selection through pump installation and seasonal maintenance. For properties with natural springs, spring development walks through spring box construction, flow measurement, and piping to your homestead.
Make it safe (purification)
Purification is about making any water source safe to drink. Boiling is the simplest and most reliable method. Filtration handles particulates and most pathogens. Chemical treatment with bleach or iodine is lightweight and inexpensive.
UV disinfection works in clear water with minimal gear. Distillation handles salt water and chemical contaminants that other methods miss. No single method covers all threats — knowing two or three makes you resilient.
Keep it on hand (storage)
Storage is about having water on hand before an emergency starts. Start with the emergency water storage fundamentals — how much you need, treatment before storage, and rotation schedules. The right containers matter more than most people realize — non-food-grade plastic leaches chemicals regardless of how well you clean it. At apartment scale, stackable 5-gallon jugs fit under beds — see apartment water storage for floor-load math, lease-friendly placement, and leak liability in rental units. At property scale, bulk storage with IBC totes holds hundreds of gallons, and permanent cistern systems capture thousands of gallons of rainwater with first-flush diverters and overflow routing.
All stored water needs treatment and a rotation schedule to stay safe. If your home plumbing is still intact, know your plumbing shutdown and bypass options. A gravity-fed distribution system eliminates pump dependency entirely — with enough elevation between your tank and your taps, water flows by pressure alone. Note that pump-dependent systems require a reliable power source; see the Energy Foundation for backup power planning. Used wash water can be repurposed for sanitation through greywater management. And when in doubt about any source, water testing tells you exactly what you're dealing with. For permanent off-grid setups, whole-house filtration integrates sediment, carbon, and UV treatment into a single household system.
When to call for expert help
Medical danger signs (dehydration → call 911 or get to an ER): confusion, no urination for 12+ hours, rapid heart rate, fainting, or unresponsiveness. Oral rehydration is not enough at this stage; severe dehydration needs IV fluids. If dehydration symptoms appear, see the Medical Foundation's assessment and triage content for immediate steps while help is en route.
Water-quality danger signs: chemical odor (gasoline, solvent, sulfur), unusual color, oil sheen, or GI symptoms within 24 hours of drinking — stop using the source and contact your county health department. Boiling does NOT remove chemical contaminants; switch to bottled water until tested.
After flooding or sewage exposure: boil all water from any source for at least 1 full minute (3 minutes above 6,500 ft (2,000 m)) before drinking, brushing teeth, or washing food, per CDC water emergency guidance. Private wells need professional testing AND shock-chlorination after a flood — see EPA Private Wells for protocols.
Vulnerable populations (infants under 1, anyone immunocompromised, dialysis patients): use bottled water of known origin until municipal supply is confirmed safe. Boiling is not sufficient if cryptosporidium contamination is possible — distillation or NSF P231 / NSF 53 filtration is required.
Field note
Identify your three closest natural water sources now and walk to each one. Measure the actual distance on foot, not by car. In a real emergency you may be carrying water back by hand — 8 gallons (30 liters) weighs 67 pounds (30 kg).
Common questions
How much emergency water should I store? At minimum, 1 gallon (3.8 liters) per person per day for 3 days — that's 12 gallons (45 liters) for a household of four. A realistic two-week target is 2 gallons (7.6 liters) per person per day to cover drinking, hygiene, and minimal cooking — 112 gallons (424 liters) for a family of four.
How long does stored water last? Commercially bottled water has a printed best-by date (typically 1–2 years) but stays drinkable indefinitely if the seal is intact. Home-stored tap water in food-grade containers lasts 6 months without re-treatment; longer if you re-treat with 8 drops of regular unscented bleach per gallon (3.8 L) and reseal. Always rotate every 6 months as the practical rule.
What containers are safe for long-term water storage? Use food-grade plastics (HDPE #2, PET #1, or PP #5) labeled for potable water, or stainless steel. Avoid milk jugs (they degrade), bleach bottles (residue), and any non-food-grade plastic — leaching is real and not visible. See containers for the full guide.
Should I boil, filter, or chemically treat water? Boil if you have fuel — it kills everything biological and is foolproof. Filter (NSF 53 or NSF P231) if you don't have heat — handles bacteria, protozoa, and most viruses depending on filter rating. Chemically treat (unscented household bleach or iodine) as a lightweight backup. No single method handles every contaminant — chemical pollution (gasoline, solvents) requires distillation. The purification decision tree walks through the choice.
Where to start
- (15 minutes) Store 1 gallon (3.8 liters) per person per day for 3 days minimum — that's 12 gallons (45 liters) for a family of four
- (20 minutes online + 2-day delivery) Buy two methods of purification: an affordable gravity filter and an inexpensive pack of purification tablets
- (30–60 minutes one weekend) Walk to your three nearest natural water sources and note the round-trip time on foot
- (2 minutes) Label every stored container with the fill date and treatment method
- (2 minutes) Set a 6-month calendar reminder to inspect and rotate stored water
With your supply secured and your sources mapped, the next step is learning practical treatment workflows with boiling, filtration, and chemical treatment — because stored water eventually runs out, and field water must be made safe before you drink it. For a structured 30-day plan that integrates water alongside shelter, food, and energy, see the First 30 Days guide.