We take our drinking water for granted in the U.S. Many of us wouldn't know what to do if disaster struck and the tap went off, if our water was contaminated and there was no heat for boiling, or if the only option was a lake, stream or maybe a puddle.

Certain parasites, bacteria and viruses that cause serious human infections live in water that appears pristine. While not all water sources have these, it's impossible to tell which ones don't.

Bringing water to a boil is a great way to kill off germs. Boiling for a minute might be overkill, but many would rather be safe than sorry. Some even advise boiling an extra minute for every 1,000 feet above sea level.

But if you don't have matches or a lighter, or wood, gas or other fuels are at a premium, other methods suffice. One is bleach. If you have some unscented bleach around the house - the kind you use for cleaning clothes - add two drops to each quart of water. Mix and let the water sit for an hour. Or you can add four drops and wait 30 minutes. If the water is cloudy or really cold, double the amount of time you wait.

No bleach? Many people have Betadine (povidone-iodine) or iodine in their first-aid kits. Add five drops of iodine or eight drops of Betadine to each quart of water and wait an hour. Or, as with the bleach, you can double the amount and wait 30 minutes. If the water is cloudy or cold, wait twice as long. Don't use this method if you think you might be allergic to iodine.

Another alternative is to buy the chlorine bleach or iodine in tablet form at a camping supply store and follow the directions on the label. It's much lighter and more portable in case you need to leave the house.

Consider a water bottle with a microfiltration system. This strains your water through tiny pores that filter bacteria and parasites. They even make a straw that does essentially the same thing. Make sure all the pores - not just some - are guaranteed to be 1 micron or less.

Viruses are so small that a microfiltration filter might not catch all of them. On the other hand, iodine and chlorine might not kill all protozoa. So it makes sense to combine the chemical and filter, if you have both.

There's one other method: the good ole sun. Set a container of water outside on a black surface. Cover the container with non-UV glass. A minimum of four hours in direct sunlight and a total of eight hours of sitting should do the trick. The more time in the sun, the better.

None of these methods will get rid of any poisons or other chemicals in the water. A charcoal filter can help, but even then, there's no guarantee.

The best plan is to have some bottled water stored for emergencies. Everyone should have 3 to 7 gallons of drinkable water stored. That should last three to seven days. Campers and hikers should plan according to their expected time away.

For more information on how to disinfect water, visit TheSurvivalDoctor.com.


Family doctor James Hubbard teaches how to survive during disasters or any time you can't get expert medical help at TheSurvivalDoctor.com