Emergency Disinfection of Drinking Water
USE ONLY WATER THAT HAS BEEN PROPERLY DISINFECTED FOR DRINKING, COOKING, MAKING ANY PREPARED DRINK, OR FOR BRUSHING TEETH
1. Use bottled water that has not been exposed to flood waters if it is available.
2. If you don’t have bottled water, you should boil water to make it safe. Boiling water will kill most types of disease-causing organisms that may be present. If the water is cloudy, filter it through clean cloths [and/or coffee filters Mr. Larry] or allow it to settle, and draw off the clear water for boiling. Boil the water for one minute, let it cool, and store it in clean containers with covers
3. If you can’t boil water, you can disinfect it using household bleach [Regular Clorox-Mr. Larry]. Bleach will kill some, but not all, types of disease-causing organisms that may be in the water. If the water is cloudy, filter it through clean cloths or allow it to settle, and draw off the clear water for disinfection. Add 1/8 teaspoon (or 8 drops of regular, unscented, liquid household bleach for each gallon of water, stir it well and let it stand for 30 minutes before you use it. Store disinfected water in clean containers with covers.
4. If you have a well that has been flooded, the water should be tested and disinfected after flood waters recede. If you suspect that your well may be contaminated, contact your local or state health department or agriculture extension agent for specific advice.
Boiling is the surest method to make water safe to drink and kill disease-causing microorganisms like Giardia lamblia and Cryptosporidium, which are frequently found in rivers and lakes.
These disease-causing organisms are less likely to occur in well water (as long as it has not been affected by flood waters). If not treated properly and neutralized, Giardia may cause diarrhea, fatigue, and cramps after ingestion. Cryptosporidium is highly resistant to disinfection. It may cause diarrhea, nausea and/or stomach cramps. People with severely weakened immune systems are likely to have more severe and more persistent symptoms than healthy individuals. Boil filtered and settled water vigorously for one minute (at altitudes above one mile, boil for three minutes). To improve the flat taste of boiled water, aerate it by pouring it back and forth from one container to another and allow it to stand for a few hours, or add a pinch of salt for each quart or liter of water boiled.
If boiling is not possible, chemical disinfection of filtered and settled water collected from a well, spring, river, or other surface water body will still provide some health benefits and is better than no treatment at all.
When boiling is not practical, certain chemicals will kill most harmful or disease-causing organisms.
For chemical disinfection to be effective, the water must be filtered and settled first. Chlorine and iodine are the two chemicals commonly used to treat water. They are somewhat effective in protecting against exposure to Giardia, but may not be effective in controlling more resistant organisms like Cryptosporidium. Chlorine is generally more effective than iodine in controlling Giardia, and both disinfectants work much better in warm water.
1. Clorox, Purex (or other brand) household chlorine bleach: regular, non scented, no dyes or additives, that contains a chlorine compound to disinfect water.
Do not use non-chlorine bleach to disinfect water. Typically, household chlorine bleaches will be 5.25% available chlorine. Follow the procedure 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 table as a guide.
• If boiling is not possible, treat water by adding liquid household bleach, such as Clorox or Purex. Household bleach which is typically between 5-6% chlorine. Avoid using bleaches that contain perfumes, dyes and other additives. Be sure to read the label.
• Place the water (filtered, if necessary) in a clean container. Add the amount of bleach according to the table below.
• Mix thoroughly and allow to stand for at least 30 minutes before using (60 minutes if the water is cloudy or very cold).
Treating Water with a 5-6 Percent Household Liquid Chlorine Bleach Solution
|Volume of Water to be Treated||Treating Long Term Municipal or Well Water: Bleach Solution to Add||Treating Cloudy, Very Cold, or Surface Water:Bleach Solution to Add|
|1 quart/1 liter||3 drops||5 drops|
|1/2 gallon/2 quarts/2 liters||5 drops||10 drops|
|1 gallon||1/8 teaspoon||1/4 teaspoon|
|5 gallons||1/2 teaspoon||1 teaspoon|
|10 gallons||1 teaspoon||2 teaspoons|
|50 gallons||5 tsp(1.6 Tbsp)||10 tsp(3.33 Tbsp)|
|57 gallons (rain water tank)||5.7 teaspoons(1.9 Tbsp)||11.4 teaspoons (3.8 Tbsp)|
|Conversions: 3 tsp=1 Tbsp; 12 tsp=1/4 cup; 4 Tbsp=1/4 cup.
• 1/8 teaspoon and 8 drops are about the same quantity.
• 60 drops per tsp; 180 drops per 1 Tbsp
• 1/8 cup (2 Tbsp) household bleach will maintain long term purity in 60 gal. water.
• ¼ cup will kill pathogens in 60 gal. filtered surface water even if cloudy and/or very cold.
• 1 quart household bleach will purify about 1000 gallons of filtered surface water
• Do not use non-chlorine bleach to disinfect water.
• Typically, household chlorine bleaches will be 5.25% available chlorine. Follow the procedure 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 table as a guide. (Remember, 1/8 teaspoon and 8 drops are about the same quantity.)
|Available Chlorine||Drops per Quart/Gallon of Clear Water||Drops per Liter of Clear Water|
|1%||10 per Quart – 40 per Gallon||10 per Liter|
|4-6%||2 per Quart – 8 per Gallon (1/8 teaspoon)||2 per Liter|
|7-10%||1 per Quart – 4 per Gallon||1 per Liter|
If the strength of the bleach is unknown:
• Add ten drops per quart or liter of filtered and settled water; or double the amount of chlorine for cloudy, murky or colored water or water that is extremely cold.).
• Mix the treated water thoroughly and allow it 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, allow the water to stand exposed to the air for a few hours or pour it from one clean container to another several times.
2. Using granular calcium hypochlorite to disinfect water
• Calcium Hypochlorite is widely available for use as swimming pool chlorine tablets or white powder that is much more stable than chlorine. This is often known as “pool shock”.
• Calcium hypochlorite is one of the best chemical disinfectants for water, better than household bleach by far. It destroys a variety of disease-causing organisms including bacteria, yeast, fungus, spores, and viruses.
• A 1-pound bag of calcium hypochlorite in granular form will treat up to 10,000 gallons of drinking water.
EPA United States Environmental Protection Agency
Procedural excerpt below pasted from: <http://water.epa.gov/drink/emerprep/emergencydisinfection.cfm>
Calcium hypochlorite Emergency Disinfection of Drinking Water Procedure
• Add and dissolve one heaping teaspoon of high-test granular calcium hypochlorite (approximately ¼ ounce) for each two gallons of water, or 5 milliliters (approximately 7 grams) per 7.5 liters of water.
• The mixture will produce a stock chlorine solution (of approximately 500 milligrams per liter, since the calcium hypochlorite has available chlorine equal to 70 percent of its weight.)
• To disinfect water, add the chlorine solution in the ratio of one part of chlorine solution to each 100 parts of water to be treated.
• This is roughly equal to adding 1 pint (16 ounces) of stock chlorine to each 12.5 gallons of water or (approximately ½ liter to 50 liters of water) to be disinfected. (Add 2 quarts stock solution per 50 gallons of water to be treated)
• To remove any objectionable chlorine odor, aerate the disinfected water by pouring it back and forth from one clean container to another.
• Granular calcium hypochlorite is corrosive and dangerous.
• Eye protection is a must when handling CH.
• Gloves and a dust mask are not essential, but it is wise to use them.
• Handle the powder in a well-ventilated area without wind.
• When dealing with corrosive chemicals it is always a good practice to have a 5 gallon bucket or sink full of water nearby to submerge your head, body or arms in case of an emergency.
When mixing CH add the CH to the water not vice-versa. It is important to go from dry to weak solution (less than 20% chlorine by weight) as fast as possible. If you only add a small amount of water to the CH it will release hazardous amounts of gaseous chlorine. If you feel a strong burning or stinging in your eyes, throat or lungs at any point, evacuate to fresh air immediately, chlorine can be deadly and was in fact used as a chemical warfare agent in WWI.
CH is a fire hazard when heated or mixed with certain organic compounds which will not be mentioned. Basically, don’t let this stuff touch anything but plastic, glass and stainless steel and you’ll be good to go.
Polyethylene (LDPE or HDPE) containers are the preferred method of storage, as this is what the CH manufacturer’s packages are made of. Nalgene makes HDPE containers that are available at most sporting goods stores (the squeezable Nalgene, look for HDPE, LDPE or UVPE marked at the bottom.)
[This is an important article to print and place in a folder for possible future reference. Mr Larry]