How to purify the essential compound of life

Water becomes especially precious during emergencies.

Last week, we covered why you need water more than any other survival item during a disaster. Most healthy people can go three weeks without food, but only three days or so without water. Water becomes especially precious during emergencies. That’s why we are devoting this month — month three of Prepare in a Year — to water.

Obtaining water on Vashon will be possible in an emergency because we have many diverse sources of H2O — seven major water providers, more than 100 neighborhood systems, and many more household wells, plus surface water from ponds and streams.

However, after an earthquake or other disaster, obtaining water may only be the first step. To keep from getting sick, you may need to make the water safe for drinking by using one of many water treatment methods. In this issue we’ll be covering four of those methods.

Reminder: You can be sure of the safe water you stored away in case of an emergency. As explained in the last issue, store at least one gallon per day for each person in your household, enough for three weeks. That’s 21 gallons per person for adequate water to cook and drink, not including water you will need for personal hygiene and sanitation.

Start with clear water

Generally, it’s best to start your water purification with clear water, free of dirt or debris. If the water is brown or cloudy, run it through a coffee filter or clean cloth to remove most particles before using one of these purification methods. They will be more effective and the water will be more palatable.

It’s important to emphasize that none of the four water purification techniques we describe here will remove chemicals or minerals. So you can’t use salt water from Puget Sound (unless you have a way to distill the water). It’s also wise to be leery of any water that may have picked up chemical pollution as runoff from a roof, driveway, or street.

Four ways to purify water


This is one of the most recommended methods to make water safe. Done right, it kills viruses, parasites, and bacteria. Bring the water to a rolling boil for at least one full minute. It’s good to have a camp stove in your household emergency kit for just this purpose in case your home cooktop is not working during an emergency.

Exposure to ultraviolet light

Properly applied, ultraviolet light can kill bacteria, viruses, algae, molds, yeasts, and cysts such as cryptosporidium and giardia. It’s crucial to follow the manufacturer’s directions to get safe water from the process, which works without chemicals or slow filtration.

Ultraviolet light treatment requires electricity, usually from batteries or USB charging, so make sure you have a source of power if you decide to rely on this method. Steripen is one well-known manufacturer of ultraviolet sterilizing water treatment devices.


Websites and stores catering to backpackers offer a wide array of water filter setups. Keep in mind that there’s a difference between merely filtering water and purifying it. If you want to be confident that you have eliminated all the potential waterborne diseases, be sure to purchase a filter system that states it purifies, which means it removes even the tiniest of bugs such as viruses.

LifeStraw, Katadyn, Sawyer, and others make purifying filters. You can get purifying filters in many sizes to produce enough water for one person or an entire family. There’s no waiting after using a purifying filter, unlike other water treatment methods. Also, a filter gets rid of dirt or other contaminating particles as an intrinsic part of the treatment process.


You can chlorinate water at home by using pure bleach. Check the label and make sure it doesn’t contain perfumes, dyes, or other additives and is labeled for “disinfecting.” Add 1/4 teaspoon of bleach to each gallon of water, and then you must let it stand for at least an hour to allow the bleach to do its purifying work.

Campers will be familiar with chlorine dioxide, recommended by the Centers for Disease Control and Prevention (CDC) as a comprehensive water treatment. Many people use a widely marketed commercial chlorine dioxide product called Aquamira, a two-part drop system also available as a tablet. Follow the instructions carefully. It takes up to 35 minutes for the treatment to have full effect.

In the last two issues, we’ve covered storing water and purifying water. In the next issue, we’ll share ways to maintain your precious safe water supply and purification systems to make sure they work when you need them.

Free health fair coming up

More than 20 sponsors will help you get healthy and stay healthy in a myriad of ways on April 27, from 10 a.m. to 2 p.m. The event, organized by the Vashon Health District, happens in just two weeks at Vashon United Methodist Church, at 17928 Vashon Highway SW.

There’s morning coffee on offer, and a free light lunch at noon. Health screenings include blood pressure, cholesterol, and blood glucose tests. You can also make contact with providers for mental health counseling, reproductive health, cancer screening, addiction prevention and treatment, caregiver support, fall prevention, and low-cost health insurance.