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.
ONLY USE WATER THAT HAS BEEN PROPERLY DISINFECTED FOR DRINKING,
COOKING, MAKING ANY PREPARED DRINK, WASHING DISHES, AND FOR
BRUSHING TEETH.
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.
- 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,
- Boil the water at a rolling boil for at least one full minute up to three
minutes.
- Allow the water to cool. When it is cool, it is ready for use.
- 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.
- 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.
- 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.
- 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.
- 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.
- Your tap water should now be safe to drink, and you can replace the faucet aerators.