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Follow a Boil Order

Emergency Disinfection of Drinking Water

In an emergency situation where regular water service has been interrupted - floods, water service interruptions, or contamination events - the Missouri Department of Natural Resources and the local public water system may recommend using only bottled water, boiled water, or for homeowners to disinfect the water until regular water service is restored.

The instructions below, compiled from several Missouri Department of Natural Resources fact sheets and EPA guidance documents, show you how to boil and/or disinfect water to kill most disease-causing microorganisms that may be present in the water. The disinfection methods listed below describe the minimum treatment required to make your water safe to drink and are the recommended procedures in communities where "boil orders" or "boil advisories" have been issued.

Please Note: boiling or disinfection will not destroy other contaminants such as chemicals, heavy metals or salts and is not appropriate when a "Do Not Drink Order" or a "Do Not Use Order" has been issued. Freezing does not disinfect water. Freezing will not kill bacteriological contaminants in drinking water. Discard all ice cubes if a boil water notice is issued.


Boil Water:

Boiling is the most effective method for killing disease-causing organisms in the water including microorganisms like Giardia lamblia and Cryptosporidium, which are frequently found in rivers and lakes.

  1.  If the water is cloudy, strain the water through a clean, tightly woven cloth into a clean container to remove any sediment or foreign material,
  2. Boil the water at a rolling boil for at least one full minute up to three minutes.
  3. Allow the water to cool. When it is cool, it is ready for use.
  4. To improve the flat taste of boiled water a pinch of salt can be added to each quart of boiled water, or pour water back and forth from one clean container into another several times.


Flushing Home Water Lines

After a flood or a water system contamination event, you may need to flush the home's internal plumbing.

  1. The best and easiest way to begin flushing your water lines is to turn on one or two outside garden faucets and let the water run for half an hour. You can use this to wash off the exterior of the house or the driveway and sidewalks. This will avoid overloading the public sewer system, or your septic system, by flushing all of the water down the household drains.
  2. Water pipes in your home that have been submerged in flood water may be extremely dirty. Clean the exterior of pipes and faucets with regular household cleaner. Remove any aerators (screens) and clean them, then briefly turn on hot and cold water at all faucets to remove dirt that may have settled just inside the faucets.
  3. Next, squirt a solution of 50 percent water and 50 percent household bleach into the faucets. Then flush all water pipes as described in Step 4. Never mix bleach with a household cleaner containing ammonia. The mixture can create a deadly chlorine gas.
  4. Sequentially flush out all water pipes inside the house. Begin at the faucet nearest the point where the waterline enters the building. This is usually the sink nearest the water meter. Turn on both hot and cold faucets at full blast for three to five minutes. Do not use water until it becomes clear. You may wish to catch water in buckets if you are concerned about overloading your septic tank. Proceed to the next nearest faucet and repeat. Continue until all faucets have been flushed. To avoid wasting hot water, wait until you have flushed all your lines to turn on your hot water heater.
  5. Your tap water should now be safe to drink, and you can replace the faucet aerators.

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