Learn · Water
Emergency Water Preparedness: How Much Water Do You Need?
Water is the most important resource in any emergency. A power outage, natural disaster or water supply disruption can quickly limit access to safe drinking water. This guide will help you understand how much water your household needs, how to store it, and how different treatment methods can make additional water safer to drink.
How Much Water Should You Store for an Emergency?
The CDC figure above is an emergency water supply recommendation. The tables below show normal daily water intake reference values — a different measurement.
Children — Daily Water Intake
| Age | Drinks / day | Total water / day |
|---|---|---|
| 1–3 years | ~0.9 L | ~1.3 L |
| 4–8 years | ~1.2 L | ~1.7 L |
| Girls 9–13 | ~1.6 L | ~2.1 L |
| Boys 9–13 | ~1.8 L | ~2.4 L |
| Girls 14–18 | ~1.8 L | ~2.3 L |
| Boys 14–18 | ~2.6 L | ~3.3 L |
1–3 years
- Drinks / day
- ~0.9 L
- Total water / day
- ~1.3 L
4–8 years
- Drinks / day
- ~1.2 L
- Total water / day
- ~1.7 L
Girls 9–13
- Drinks / day
- ~1.6 L
- Total water / day
- ~2.1 L
Boys 9–13
- Drinks / day
- ~1.8 L
- Total water / day
- ~2.4 L
Girls 14–18
- Drinks / day
- ~1.8 L
- Total water / day
- ~2.3 L
Boys 14–18
- Drinks / day
- ~2.6 L
- Total water / day
- ~3.3 L
Adults — Daily Water Intake
| Adult | Drinks / day | Total water / day |
|---|---|---|
| Women 19+ | ~2.2 L | ~2.7 L |
| Men 19+ | ~3.0 L | ~3.7 L |
Women 19+
- Drinks / day
- ~2.2 L
- Total water / day
- ~2.7 L
Men 19+
- Drinks / day
- ~3.0 L
- Total water / day
- ~3.7 L
“Total water” includes water obtained from both beverages and food. “Drinks / day” figures represent water from beverages, not necessarily plain drinking water alone. These are general reference values, not individualized medical targets.
Household water calculator
- Adult 1
- Adult 2
- Child 1
CDC Emergency Water Recommendation
Official referenceAt least 1 gallon (3.8 L) per person per day for at least 3 days.
Source: CDC. Not calculated from your household's age and sex.
Estimated Daily Drinks
Complete household details to calculate daily drinks.
Based on household age and sex reference values.
Estimated Drinks for
Days
Complete household details to calculate drinks.
Daily drinks × 3 days. Drinks only — not all emergency water uses.
Drinking needs and emergency water storage are different. CDC emergency water guidance also accounts for water needed beyond drinking alone.
Where Can Emergency Water Come From?
Stored potable water
Water already stored and safe for drinking when properly maintained.
- Collection
- Not required
- Treatment
- Ready to drink
Tap water
Safety varies by country, local water quality and current advisories.
- Collection
- Not required
- Treatment
- Ready to drink / Required
Rainwater
Rain can provide emergency water when it can be safely collected and stored.
- Collection
- Required
- Treatment
- Required
River / lake / stream
Surface water may contain microorganisms and other contaminants.
- Collection
- Not required
- Treatment
- Required
Air / atmospheric water
Water can be extracted from humid air using specialized equipment.
- Collection
- Equipment required
- Treatment
- Depends on system
Seawater
Seawater can provide a potential water source in coastal areas, but its salt must be removed before drinking.
- Collection
- Not required
- Treatment
- Desalination required
💧 How water works
Different water sources require different capabilities before they become usable or safe drinking water.
↓ Untreated
↓ Untreated
↓ Untreated
🧺 Utility water
May suit some non-drinking uses, depending on quality and use.
🛡️ Treatment system
💧 Drinking water
Also from drinkable tap water
Water availability does not always mean safe drinking water. Source, collection, treatment and storage capabilities all matter.
How to Make Water Safe to Drink in an Emergency
Different water treatment methods protect against different hazards. The right method depends on the water source, the contaminants present and the specific treatment system being used.
Emergency Water Treatment Methods Compared
| Method | Bacteria | Viruses | Protozoa | Chemicals / Metals | Salt | Energy / Dependency |
|---|---|---|---|---|---|---|
| Boiling | ✓ | ✓ | ✓ | ✕ | ✕ | Heat |
| Microfiltration / Portable Filter | ✓* | ✕ generally | ✓* | ✕ generally | ✕ | Manual / none |
| Ultrafiltration / Purifier | ✓ | ✓ if designed/certified for viruses | ✓ | ✕ generally | ✕ | Depends on system |
| Chlorine / Chlorine Dioxide | ✓ | ✓ | ⚠ Depends on product / parasite | ✕ | ✕ | None |
| Household Bleach | ✓ | ✓ | ⚠ Limited | ✕ | ✕ | None |
| UV Treatment | ✓ | ✓ | ✓ | ✕ | ✕ | Battery / electricity |
| Reverse Osmosis (RO) | ✓* | ✓* | ✓* | ✓ Many | ✓ | Pressure / electricity / manual |
| Distillation | ✓ | ✓ | ✓ | ✓ Many, not all | ✓ | High heat / electricity |
| Portable RO Desalination | ✓* | ✓* | ✓* | ✓ Many | ✓ | Manual / electricity |
Boiling
- Bacteria
- ✓
- Viruses
- ✓
- Protozoa
- ✓
- Chemicals / Metals
- ✕
- Salt
- ✕
- Energy / Dependency
- Heat
Microfiltration / Portable Filter
- Bacteria
- ✓*
- Viruses
- ✕ generally
- Protozoa
- ✓*
- Chemicals / Metals
- ✕ generally
- Salt
- ✕
- Energy / Dependency
- Manual / none
Ultrafiltration / Purifier
- Bacteria
- ✓
- Viruses
- ✓ if designed/certified for viruses
- Protozoa
- ✓
- Chemicals / Metals
- ✕ generally
- Salt
- ✕
- Energy / Dependency
- Depends on system
Chlorine / Chlorine Dioxide
- Bacteria
- ✓
- Viruses
- ✓
- Protozoa
- ⚠ Depends on product / parasite
- Chemicals / Metals
- ✕
- Salt
- ✕
- Energy / Dependency
- None
Household Bleach
- Bacteria
- ✓
- Viruses
- ✓
- Protozoa
- ⚠ Limited
- Chemicals / Metals
- ✕
- Salt
- ✕
- Energy / Dependency
- None
UV Treatment
- Bacteria
- ✓
- Viruses
- ✓
- Protozoa
- ✓
- Chemicals / Metals
- ✕
- Salt
- ✕
- Energy / Dependency
- Battery / electricity
Reverse Osmosis (RO)
- Bacteria
- ✓*
- Viruses
- ✓*
- Protozoa
- ✓*
- Chemicals / Metals
- ✓ Many
- Salt
- ✓
- Energy / Dependency
- Pressure / electricity / manual
Distillation
- Bacteria
- ✓
- Viruses
- ✓
- Protozoa
- ✓
- Chemicals / Metals
- ✓ Many, not all
- Salt
- ✓
- Energy / Dependency
- High heat / electricity
Portable RO Desalination
- Bacteria
- ✓*
- Viruses
- ✓*
- Protozoa
- ✓*
- Chemicals / Metals
- ✓ Many
- Salt
- ✓
- Energy / Dependency
- Manual / electricity
- ✓
- Effective for this hazard when the method/system is appropriate and used correctly.
- ✕
- Not designed to reliably address this hazard.
- ⚠
- Effectiveness varies or has important limitations.
- *
- Performance depends on the specific device, membrane/pore size, certification and correct use.
Sources & References
- CDC — How to Make Water Safe in an Emergency (external link, opens in a new tab) ↗
- CDC — Water Treatment Options When Hiking, Camping or Traveling (external link, opens in a new tab) ↗
- CDC — About Home Water Treatment Systems (external link, opens in a new tab) ↗
- EPA — Emergency Disinfection of Drinking Water (external link, opens in a new tab) ↗
- EPA — Overview of Drinking Water Treatment Technologies (external link, opens in a new tab) ↗
- WHO — International Scheme to Evaluate Household Water Treatment Technologies — Resources (external link, opens in a new tab) ↗
- WHO — Household Water Treatment Evaluation Results (external link, opens in a new tab) ↗
- LifeStraw — What is the Difference Between a Filter and a Purifier? (external link, opens in a new tab) ↗
- LifeStraw — How Do LifeStraw Membrane Ultrafilters (Water Purifiers) Work? (external link, opens in a new tab) ↗
Boiling Water During an Emergency
Water Filters vs Water Purifiers
What About a Water Outage?
Test Your Household's Water Readiness
Build Your Emergency Water Supply
Potable Stored Water
Stored drinking water should be the foundation of your emergency water supply. Commercially bottled water is a safe and reliable option when kept unopened. You can also store water yourself in clean, food-grade containers designed for water storage.
Water Containers and Storage
Use food-grade water storage containers with tight-fitting lids. Avoid containers that previously held toxic chemicals. Store emergency water in a cool location away from direct sunlight and substances such as gasoline, pesticides or household chemicals.
Storage Practices
Keep enough water for every person in your household and check your supply regularly. Replace commercially bottled water according to its expiration or best-by date. For water stored in your own containers, the CDC recommends replacing it every 6 months.
Tip: Store water in containers that are practical to lift, carry and use during an emergency.