Mon - Fri: 8:00 - 4:30

All LCDHD Locations

(800) 295-8253

After Hours Public Health Emergency Hotline


Employee Portal

Main Menu

Lake Cumberland District Health Department

A healthy today for a brighter tomorrow.

Disinfect Drinking Water

The Lake Cumberland District Health Department would like to offer this information to help the community be prepared in the event of a disaster or natural emergency.

For homeowners, the water supply may become interrupted during a disaster or natural emergency leaving the homeowner searching for a source of water.  Homeowners should learn about disaster preparedness before an emergency arises.  Contact the Kentucky Department of Emergency Management at 800-255-2587 before an emergency occurs about how your family should be prepared.  Also, the Kentucky Cabinet for Health and Family Services offers food and water safety recommendations for severe weather and other emergencies.  For more information, call your local health department at 606-679-4416 or call the Food Safety Branch in Frankfort at (502) 564-7181.


One way to prepare ahead of time for a disaster is to assemble a family disaster supply kit.  This kit should contain seven basic items – water, food, first aid supplies, clothing, bedding, tools and any special medications.  Keep items you would most likely need during an evacuation or disaster in an easy-to-carry container such as a large covered trash can, a large cooler, a camping backpack or a duffel bag.  The large trash can or cooler might come in handy for other uses during the emergency.

Stocking up on bottled water should be part of a family disaster plan.  Store at least one gallon of water per person per day (three days minimum).  Other sources of water would be well water and water haulers.  If you contact someone to haul water, make sure the tank is cleaned and disinfected.

If river or lake water must be used, avoid sources containing floating material and water with a dark color or an odor.  When emergency disinfection is necessary, examine the physical condition of the water.

Disinfectants are less effective in cloudy water.  Filter murky or colored water through clean cloths, cheese cloth, or allow time for the sediment to settle, then draw off the “clean,” settled water for disinfection.  Water prepared for disinfection should be stored only in clean, tightly covered containers not subject to corrosion.

There are two general methods by which small quantities of water can be effectively disinfected.  One method is boiling.  It is the most positive method by which water can be made bacterially safe to drink.  Another method is chemical treatment.  If applied with care, certain chemicals will make most water free from harmful or pathogenic organisms.

Methods of Emergency Disinfection:

Boiling:  Vigorous boiling for one minute will kill any disease-causing microorganisms present in water (at altitudes above one mile, boil for three minutes).  The flat taste of boiled water can be improved by pouring it back and forth from one disinfected container to another (process called aeration).  Allowing the boiled water to stand for a few hours or adding a small pinch of salt for each quart of water boiled will also help improve the flat taste.

Chemical Treatment:  When boiling is not practical, chemical disinfection is an option to consider.  The two chemicals commonly used are chlorine or iodine and are effective at removing harmful pathogens.

Be aware that these disinfectants are not effective or only somewhat effective in controlling Cryptosporidium and Giardia found in surface water.  These two pathogens are only found in water from rivers, lakes and springs.  Therefore, chlorine or iodine should be used to disinfect well water since Cryptosporidium and Giardia are unlikely to be found in well water.

CHLORINE BLEACH:  When boiling is not practical, chemical disinfection should be used. Common household bleach contains a chlorine compound that will disinfect water. The procedure to be followed is usually written on the label. When the necessary procedure is not given, find the percentage of available chlorine on the label and use the information in the following tabulation as a guide.

Available ChlorineDrops per Quart of Clear Water

(If strength [percentage] is unknown, add ten drops per quart of water. Double amount of chlorine for cloudy or colored water or water that is extremely cold.)

The treated water should be mixed thoroughly and allowed to stand, preferably covered, for 30 minutes. The water should have a slight chlorine odor; if not, repeat the dosage and allow the water to stand for an additional 15 minutes. If the treated water has too strong a chlorine taste, it can be made more pleasing by allowing the water to stand exposed to the air for a few hours or by pouring it from one clean container to another several times.

[Another method of disinfecting small quantities of drinking water is as follows: Using a 5.2% of Clorox or Purex, add 5 teaspoonfuls to one quart of water to prepare a stock solution.  This should be placed in a tightly stoppered bottle and kept away from the light.  To disinfect drinking water, add one teaspoonful of this stock solution to one gallon of water, stir the water thoroughly and allow to stand for thirty minutes.]

CHLORINE TABLETS:  Chlorine tablets containing the necessary dosage for drinking water disinfection can be purchased in a commercially prepared form. These tablets are available from drug and sporting goods stores and should be used as stated in the instructions. When instructions are not available, use one tablet for each quart of water to be purified.



To disinfect a cistern, add regular household laundry bleach (at least 5.2% available chlorine) at the rate of 1 pint (16 fluid oz) per each 3,000 gallons of water.  Volume in gallons in a rectangular (box-shaped) cistern is determined by using the formula:

Length × Width × Depth of Water × 7.5 = Total Gallons

Pour the pre-determined amount of chlorine bleach into a 5 gallon pail or other suitable container.  Fill with water and pour the disinfecting solution into the cistern.  This cistern should be agitated or stirred to assure equal distribution of the disinfecting solution.  After approximately 30 minutes of contact time, the treated cistern water should be safe to use.  A slight taste or odor of chlorine may be present in the water after treatment.  This should disappear within 24-36 hours.

To determine the number of gallons in a round (cylinder-shaped) cistern, use the following formula:

Radius × Radius × 3.14 × Depth of Water × 7.5 = Total Gallons

To properly disinfect a well, use regular household laundry bleach (at least 5.2 % available chlorine).  Add bleach at the rate of 1 cup (8oz.) per 300 gallons of standing water in the well.  After adding the necessary amount of chlorine, wait for 30 minutes before pumping the well.  Pumping should continue until the odor of the chlorine disappears.

The above disinfecting procedure should make the water safe for drinking until bacteria infiltrates the supply again.  A chlorinator, a small pumping device which continuously pumps chlorine into the water supply, or other means of pretreatment is recommended as a permanent solution to the problem.

This information on emergency disinfection of drinking water was prepared through resources provided by the U.S. Environmental Protection Agency. Contact your local health department at 606-679-4416 or the Kentucky Department of Emergency Management at 800-255-2587 for recommendations during an emergency and how to be prepared.