Published: May 19, 2009 11:01 am      

Health officials say water supplies affected by flooding need disinfecting

Public and private water supplies around the state have been affected by the massive flooding to hit West Virginia recently. Because flood waters carry disease-causing organisms that can lead to serious illness or even death, officials from the Bureau for Public Health and local health departments have been working to ensure that all water systems are operational and safe.

“Boil water advisories” have been issued for a limited number of communities served by public water supplies. That means water should be heated to a rolling boil and boiled for one minute before it is safe for drinking and other domestic uses. The taste may be improved by pouring the water back and forth from one clean container to another, by allowing it to stand for a few hours, or by adding a pinch of salt to each quart of boiled water.

Water may be treated with chorine or iodine tablets, or by mixing 10 drops (quarter teaspoon) of unscented, ordinary household chlorine bleach (5.25 percent sodium hypochlorite) per gallon of water. Mix well, and let stand for 30 minutes. It should have a distinct taste or smell of chlorine. If this is not present, add 10 more drops and allow to stand for 15 minutes. Do not use the water if you cannot detect chlorine in it. However, this process does not kill parasitic organisms.

Officials are also warning that precautions should be taken with private water supplies. All wells, springs, cisterns, pumps and pipes that have been exposed to flood water must be disinfected. This can be accomplished using common laundry bleach labeled to contain 5.25 percent available chlorine. A five gallon batch of disinfecting solution can be prepared mixing one gallon of bleach with four gallons of water.

To disinfect the water supply, first remove all debris from the well, spring, cistern or reservoir. Then pour half (2.5 gallons) of the disinfecting solution into the supply. Start the pump, and open all taps until the water from each tap has a distinct chlorine odor, then close the taps. Pour the remaining 2.5 gallons of the solution into the water supply and allow the solution to remain in the water for 12 to 24 hours. Do not use any water from the supply for at least 12 hours. After the waiting period, pump the water supply to waste until the chlorine odor disappears, and it should then be safe for use. However, this disinfecting process is only temporary and only water in the supply at the time of treatment is disinfected. Fresh water entering the supply may also be contaminated, so to ensure safety there should always be a slight taste of chlorine present in the water.

A sanitarian should collect samples for testing before the water is used. Improperly protected supplies can be unsafe, and immediate steps should be taken to abandon or reconstruct such supplies, so they will be protected against further contamination.

For more information about flood clean-up procedures, go online to www.wvdhhr.org/phs/disaster/index.asp or call your county health department.