Get prepared for the Cascadia earthquake and tsunami by taking our free course, Preparing for the Cascadia Subduction Zone Event.
Natural disasters can occur at any time and without warning. These unexpected emergencies often cause temporary loss of power and utilities. When these disruptions occur, we need to be able to live without modern conveniences like potable water, electricity, natural gas and fuel.
One disaster that officials are gearing up for is the Cascadia Subduction Zone earthquake.
Scientists say there is a 37% chance that a major earthquake will occur along the Oregon Coast sometime within the next 50 years. The earthquake is expected to come from a rupture of the 600-mile fault called the Cascadia Subduction Zone, which sits from 70 to 100 miles off the Pacific Coast.
This publication, along with others in the Creating a Culture of Preparedness series, are part of Oregon State University Extension Service’s free online training, Preparing for the Cascadia Subduction Zone Event. The sessions (beav.es/Cascadia) are open to everyone. They include videos, narrated presentations, simulations, interactive maps, articles and other resources exploring what the earthquake and tsunami will be like and how those affected can recover.
After the earthquake, many Oregonians may be without utilities for weeks or months. Consequently, the Oregon Office of Emergency Management has launched a campaign — titled “2-Weeks Ready” — to encourage Oregon residents to set aside two weeks’ worth of food, water, medicines and other supplies.
In some areas, four weeks of food and water are recommended. Check with your local emergency manager. When everyone prepares, emergency responders can focus their limited resources on injured or vulnerable populations after a disaster.
In this publication, we explore a variety of methods for purifying and storing water for an extended emergency. We’ll also discuss how to find or make safe water from additional sources.
Each person uses roughly a gallon of water per day for drinking, meal preparation, cleanup and personal hygiene. Individual needs vary by age, activity level, health, diet and climate.
The Centers for Disease Control also recommend 1 gallon of water for most common household pets. Therefore, plan to store 1 gallon of water per day for each person and pet in the household for a minimum of three days and preferably two to four weeks. For example, four human members and two animal members of a household will need 6 gallons of water per day stored.
This is a conservative amount, and you will need to use it wisely. Consider practicing and only using stored jugs of water for a few days to see how much water your household uses.
For the recommended two weeks, plan to store 14 gallons per person and pet. For each individual, you will need two 7-gallon, camping-style water containers, 14 1-gallon jugs, 27 2-liter bottles or 53 1-liter bottles.
When choosing containers, consider how they will be used. Can the water be poured easily from the container? One gallon of water weighs 8.3 pounds. Will the water jugs be too heavy to transport if you are evacuated?
Water can be purchased in large containers for emergency purposes. Follow directions for storing and observe the expiration date.
Using your own containers for water storage is less expensive, however. When storing tap water for emergencies, use screw-top containers manufactured for food use (such as plastic soda bottles, juice bottles or water jugs).
Do not use repurposed plastic milk jugs. They are made from biodegradable plastic that could develop leaks. Also, protein from the milk can cause the stored water to spoil. Glass containers can also break. Commercially bottled water should be replaced every six months for quality purposes.
The best option is to use food-grade, heavy-duty plastic buckets, carboys or drums stamped with a PETE or HDPE recycle code.
All containers used for storing water need to be sanitized before adding potable water.
City water from municipal water sources is already treated to be safe, so no additional treatment is necessary. Fill the clean, sanitized, food-grade container with tap water and close securely.
Water from a well or spring, known to be pathogen-free but not chemically treated, should be purified by boiling or adding unscented, household, liquid chlorine bleach.
Stir the mixture well. Let it stand for at least 30 minutes before you use it. Store the purified water in clean, sanitized containers with tight covers.
Label the container with the words “Drinking Water” and the date stored. If utilizing large containers for long-term water storage, use the following water-to-bleach ratios to ensure the water is sanitized:
Purify water
Container size
Amount of bleach
5 gallons
3/4 teaspoon
7 gallons
1 teaspoon
15 gallons
2 teaspoons
55 gallons
2 tablespoons
Storage conditions
It is best to store the water in a dark, dry, consistently cool space. At the very least, store the water in an environment that stays at a constant temperature and is out of direct sunlight. Store water away from cleaning supplies, fertilizer and any product with strong odors. These odors can be absorbed by the storage container and transferred to the water.
Tip: A freezer is most efficient when it is full. Fill empty spaces with food-grade plastic or metal containers of water. Let the water freeze, then cap the container. This serves many purposes:
Once the container is opened, use the water rather than re-storing it. If stored water has a flat taste, pour it back and forth between two clean containers several times to reoxygenate it. Taste changes over time, so follow the best-by dates on store-bought water and replace water in your own containers every six months. Repurpose your “expired” water by using it in the garden or for cleaning.
In the event of a widespread, devastating event like the Cascadia Subduction Zone earthquake, your emergency water supply may not be enough, and you will need to obtain water from other sources.
If authorities warn that public water is unsafe, or if there are signs of broken water lines, shut off the water lines entering the home. This prevents unclean water from entering your home’s water system and contaminating the usable water inside your home. Keep in mind:
There are several water sources in our environment:
When using these sources, choose quickly-moving springs and rivers first. They have fewer pathogens than lakes, ponds and most rainwater-collection barrels. However, the water from springs, rivers and other natural sources must be purified to drink.
Avoid water with floating materials, an odor or dark color. Do not use floodwater. Water contaminated with fuel or toxic chemicals cannot be made safe by boiling or disinfection.
When in doubt about water’s quality, purify it. Except for boiling, few water treatments remove all pathogens. If the water is cloudy or has visible debris, let it settle then filter it through a clean cloth, cheese cloth, jelly bag, paper towel or coffee filter.
Boiling is the best way to make water safer to drink. Boiling kills viruses, bacteria and parasites that can cause disease and illness. Follow directions in the “Preparing water for storage” section on page 2.
Disinfecting with chemicals kills viruses, certain bacteria, mildew and fungi. It will not remove bad taste or debris. If boiling water is not possible, use a combination of filtration and chemical disinfection. When using these methods, follow the manufacturer’s instructions carefully.
Follow directions to disinfect in “Preparing water for storage” section on page 2. Powdered drink mixes such as Kool-Aid or Crystal Light mask the flavor of disinfected water, so keep some in your emergency kit.
Water disinfected with iodine is NOT recommended for pregnant women, people with thyroid problems or those with hypersensitivity to iodine. No one should continuously use iodine for more than a few weeks at a time.
A combination of filtration and purification removes and kills pathogens.
Distillation: While boiling and chlorination will kill most microbes in water, distillation will remove microbes (germs) that resist these methods. Distillation also removes heavy metals, salts and most other chemicals. Distillation involves boiling water and then collecting the vapor that condenses. The condensed vapor will not include salt or most other impurities.
To distill, fill a pot halfway with water. Tie a cup to the handle on the pot’s lid so that the cup will hang right-side-up when the lid is upside-down (make sure the cup is not dangling into the water) and boil the water for 20 minutes. The water that drips from the lid into the cup is distilled.
Filtering mechanically removes contaminants. Most filters can remove everything but viruses.
Many portable water filters can remove many pathogens. When choosing a portable water filter, pick one that has an absolute pore size of less than or equal to 1 micron. Another option is to choose one that has been tested and certified to a National Sanitation Foundation and American National Standards Institute Standard 53 or 58 for cyst reduction and cyst removal. You can also choose one that uses reverse osmosis. Most filters will not remove bacteria or viruses.
Carefully follow the manufacturer’s instructions for your water filter. After filtering, add a disinfectant such as iodine, chlorine or chlorine dioxide to the filtered water to kill any viruses and remaining bacteria.
Note: Filters collect germs from water, so someone who is not immunocompromised should change the filter cartridges. Anyone changing the cartridges should wear gloves and wash hands afterwards. Poor filter maintenance or failure to replace the filter cartridges as recommended by the manufacturer can cause a filter to fail.
Other treatment methods can be effective against some pathogens, including:
Emergency water distribution sites will likely be set up in many Oregon communities after the disaster. Your local emergency manager should be able to direct you to it.
Store at least the recommended amount of safe water before the disaster. After the disaster, water can be found from other sources.
Water can be made safe by boiling, disinfecting or a combination of filtering and disinfecting. Keep water in all of your disaster kits.
Know when and where community food and water distribution sites are planned for your community. Keep in mind:
Visit the Centers for Disease Control for more information and to learned how to select an an appropriate water filter.
Project supported by National Institute of Food and Agriculture Smith Lever Special Needs Competitive Grants Program (Award# 2018-41210-28702).
