Tips on Water Safety During and After a Storm

Editor's note: Food process engineer Dr. Timothy Bowser, a faculty member in Oklahoma State University's Department of Biosystems and Agricultural  Engineering and an Advisory Board member of Shelf Life Advice, provided the following remarks for this site.

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Water is one of the biggest food issues after any large storm.  Municipal water sources can be polluted and may endanger those that drink contaminated water or wash food or hands with it prior to treating the water.  After a major storm or disaster, assume that the water from your public water system is unsafe to drink or use for cooking until you've heard an official announcement that the water is safe.   

It is not a good idea to wash your hands in dirty water. The soap will remove the soil and bugs, but pathogens may return with the rinsing. After a wash and rinse in clear water that may be contaminated, it's a good idea to use a hand sanitizer. The sanitizer, when applied properly, will be very effective.

Showering is a similar issue. When I travel internationally, I frequently bathe and shower in contaminated water (not potable) because nothing else is available. You can do the same, but keep polluted water out of your eyes, nose, mouth, and any cuts. In reality, it’s just a matter of time till you swallow some or get it in your eyes.

Some government websites advise using bleach treatment to decontaminate water after a hurricane and/flooding. To do this, add 1/8 teaspoon (or 8 drops) of regular, unscented, liquid household bleach for each gallon of water, stir it well and let it stand for 30 minutes before you use it. Store disinfected water in clean containers with covers.

You would definitely want clear water prior to using a bleach treatment. Organic materials in the water would inactivate the bleach, reducing its availability to kill organisms.  Bleach can kill bacteria, but it won't clear up most chemicals (e.g. fuel, antifreeze) or remove odors (e.g. sewage, animal corpses). 

Most of the water treatment equipment one needs can be obtained at sporting goods or outdoor sports stores. They usually sell water purifiers for backpackers and travelers. Many types are available. My favorite water purifiers are the ones made by General Ecology (generalecology.com). I have a lot of experience with their equipment and find it very safe and reliable. 

Reverse Osmosis is a microfiltration method that uses membranes and pressure to filter water down to the sub-micron level. Bacteria are typically 0.2 to 1 micron and viruses are 0.02 to 0.4 micron in diameter. RO membranes filter down to about 0.005 microns. Pressure is used to force water through the membrane. The contaminants are concentrated on the “dirty’ side of the membrane and water passes through.

A good method for water treatment (when RO is not available) is to use a carbon filter followed by an absolute filter that removes particles greater than 0.1 micron. Some filters designed for travelers work this way. This system will take out all bacteria and cysts, some chemicals, and flavors. 

Boiling water is also helpful. Viruses, cysts, and bacteria can be inactivated by heating water to boiling. Boiling will also serve as a safeguard for mistakes in the filtration/handling process. At sea level, be certain to achieve a rolling boil for 60 seconds. Altittudes above 1 mile require 3 minutes of boiling.

The biggest mistakes are usually made when clean drinking water surfaces (cups, bowls, water purifier discharge, etc.) are contaminated by untreated water.  Also, any unsealed food that has been touched by flood water must be discarded.

For more information on handling water after a storm, check this site:

http://www.fda.gov/Food/ResourcesForYou/Consumers/ucm076993.htm.