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Here we describe how to use household bleach or bleach of other strengths to disinfect water for emergency drinking water use. We also explain how people deal with the risk of Cryptosporidium in drinking water. This article series outlines methods to purify or sanitize drinking water in an emergency following a disaster such as an earthquake, flood, or hurricane. A companion article, DRINKING WATER - EMERGENCY SOURCES,describes possible sources of drinking water that may be useful in emergency conditions.

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Using Bleach as a Disinfectant for Water Purification

Chlorine bleach (sodium hypochlorite) Iodine alternatives for disinfectants include chlorine-based products (bleach) and non-iodine-based water filters. Commercial bleach such as laundry bleach purchased at a supermarket contain 3 to 6% sodium hypochlorite. Be sure that bleach to be used to purify drinking water contains only sodium hypochlorite. For example, do not use a bleach-soap mixture.

How much bleach do we need to purify drinking water? It depends on the concentration (strength) of the bleach solution you're using as well as the condition of the water. If you don't know your store-bought household bleach solution strength, use 10 drops per gallon of water and let the solution stand for 30 minutes. If after 30 minutes there is absolutely no chlorine or "bleach" smell in the water, repeat the dose and let the solution stand for another 30 minutes.

Below at How much disinfectant to use in drinking water? we review the amount of bleach or other disinfectants needed in more detail.

Chlorine does kill Giardia cysts if used in high enough concentration and for sufficient contact time, but typically the chlorine concentration in water necessary for Giardia would be too high for drinking purposes.

The chlorine concentration that one would find in a swimming pool, levels of chlorine not suitable for drinking water consumption would require about 20 minutes to kill a Giardia cyst.

Cryptosporidium cysts might survive a typical chlorine disinfection process (such as at a municipal water treatment plant).

For this reason some municipalities where Cryptosporidium cysts are a concern add a water treatment step using chlorine dioxide. Others may use a combination of UV light and chlorine in the water treatment procedure. This treatment is also available to hikers, travelers, and for emergency water supply use.

Aquamira™ and Katadyn™ (Micropur) provide portable or field-use water treatment kits using chlorine dioxide.

How to Remove the Bleach Odor from Disinfected Water

Do not attempt to remove the chlorine or iodine taste from water until the water has completed its treatment wait period.

Boil the water for a few minutes. Heat will speed the decomposition of the bleach in the water. If you have no heat source let the water stand open for a few hours.

Pour the water back and forth between clean containers - the aeration process will speed the release of the chlorine odor and taste from the water. Iodine treated water won't have such a strong taste but you can improve the taste of treated water further with a small pinch of salt or by mixing in a drink powder like lemonade.

Add vitamin C to the water, or a drink that contains vitamin C.

Also see Wait Time & Water Temperature When Adding a Disinfectant - Before Drinking the Water where we provide more details about how to use bleach as a disinfectant.

Vegetable Disinfection Washes & Treatments

Vegetable disinfecting wash chemicals sold at many produce stores or grocery stores (Sin Bac™, for example, is a product we use in Mexico) often contain a chemical (Cloro Dimetil Hidantonia or 1-Bromo-3-chloro-5,5-dimethyl-Hydantoin is a mixture of chlorine and bromine to form a useful antiseptic agent having bacteriostatic and bacteriacidal capabilities that have antibacterial, antifungal, antiprotozoal, and anthelmintic activity) that can be used to disinfect water for drinking. If you have one of these products, read the label for the required amount of chemical to add and the wait time to use before consuming the water. Typically the products that we have used contain iodine.

• When disinfecting leafy vegetables that may also be dirty with soil or sand, we rinse them off thoroughly with tap water, or we repeat the disinfection process twice.
• When disinfecting lettuce we cut the head of lettuce into halves or quarters and immerse the lettuce by placing a dish on top of the vegetables in the soak-bowl during the disinfection period. Lettuce can then simply be drained in a dish drainer before it is stored.
• Don't cut the disinfection time or solution concentration below that recommended by the manufacturer or you may not be adequately disinfecting your vegetables.
• After vegetables or fruits are disinfected by your solution, do not rinse them off with tap water. Simply let them dry. Rinsing risks re-infecting the food.
• Be sure that the cutting board you use to prepare vegetables or any other food has been thoroughly washed, and in particular, be sure it and your knives are thoroughly cleaned after cutting meat or poultry, before using the same board and knives again to cut and prepare your disinfected vegetables.
• 1-Bromo-3-chloro-5,5-dimethylhydantoin (C5H6BrClN2O2) is produced world-wide and is also used in cleaners and bathroom disinfectants and deodorizers. Here is an example MSDS for this product, provided by Leisure Time. We like the Sin Bac™ product in part because the soak time for vegetables (one cap of disinfectant per liter of water) is just five minutes. Some other vegetable disinfectant solutions require 10 or even 15 minutes of soaking.

Vinegar may be effective as a limited-scope disinfectant wash for vegetables as well. See Vinegar & Other Disinfectants for details.

Also see Wait Time & Water Temperature When Adding a Disinfectant - Before Drinking the Water where we provide more details about how to use bleach as a disinfectant.

Links provided just below continue with details about various methods to disinfect or purify emergency drinking water.

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ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
FLOODS & MOLD CLEAN/PREVENT A Guide to Dealing with Flood Damage & Mold Prevention &r Cleanup of Flooded Homes
  FIRST PRIORITIES When Responding to a Flooded Building
  BUILDING ENTRY PROCEDURE How to Enter a Building After a Building Flood
  DRINKING WATER - EMERGENCY PURIFICATION How to purify emergency drinking water, how to remove odors
    How to Purify Water
    Boiling Water for Drinking
    Iodine Tablets or Iodine Disinfectant
    Bleach as a Disinfectant for Drinking Water
    Vegetable Disinfection Washes
    Hydrogen Peroxide for Water Disinfection
    Vinegar & Other Disinfectants
    How Much Disinfectant to Use
    Wait Time & Water Temperature
    Filters for Drinking Water Purification
    Giardia in Drinking Water
  DRINKING WATER - EMERGENCY SOURCES Where to find drinking water in an emergency
  ELECTRICAL SAFETY for Flood Damage Inspectors
  FLOOD DAMAGE TO FOUNDATIONS
  FLOOD RESPONSE CHECKLIST Checklist of Key Steps to Minimize Mold Damage After a Building Flood
  INEFFECTIVE MOLD PRODUCTS Ineffective Mold Products and Procedures to Avoid in Mold Cleanup/Prevention
  FURTHER STEPS PREVENT MOLD Further Steps to Avoid Mold Damage After a Building Flood
  WHEN TO STOP LOOKING FOR MOLD after Flooding: When is a Mold Cleanup Job Complete?
  GENERAL MOLD PREVENTION Preventing Future Mold After a Flooded Building Cleanup
  FLOOD DAMAGE RFERENCES References on Mold Prevention and Flood Damage
  FLOOD VENTS How to Use Flood Vents for Structural Protection from Flooding - Flood Venting in Foundations and Enclosures Below Design Flood Elevation
  SEPTIC SYSTEMS & FLOODS What to Do after a Flood - Septic Flood Response, Safety, Health, Maintenance, Repair Advice
  SEWAGE CONTAMINATION IN BUILDINGS how to detect and respond to sewage backups
  SEWAGE PATHOGENS in SEPTIC SLUDGE what are the contaminants in sewage
  Wind Damage to Roofs how to assess and identify wind damage to roofs
PLUMBING TOPICS
WATER TREATMENT EQUIPMENT CHOICES
WELL CHLORINATION SHOCKING PROCEDURE

• Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com 11/06
• Hankey and Brown home inspectors, Eden Prairie, MN, technical review by Roger Hankey, prior chairman, Standards Committee, American Society of Home Inspectors - ASHI. 952 829-0044 - hankeyandbrown.com 11/06
• Dr. Omar Amin, of the Tempe AZ Parasitology Center, corresponded with one of our readers asking about peroxide: "You can use hydrogen peroxide if you want to but we do not have a track record of percentage dilution". Dr. Amin has done research for the US military and for the CDC.
• Potable Aqua® emergency drinking water germicidal tablets are produced by the Wisconsin Pharmacal Co., Jackson WI 53037. 800-558-6614 pharmacalway.com
• Aquamira™ chlorine dioxide water purification kits - see www.aquamira.com/
  "Aquamira Water Treatment Drops were introduced to the Outdoor market in 1999 and have been a favorite of top outdoor guides and instructors ever since. Whether you are camping, traveling in a foreign country or faced with a disaster, our goal is to provide you with safe, pure and good tasting drinking water. Our complete line of water treatment products include leading edge purification and filtration technologies developed and tested in the lab and proven in the field. We offer systems and products that will provide water for a single individual or a village and almost anything in between."
  
• Katadyn™, a Swiss corporation provides water filters, desalinization equipment, and their Micropur chlorine dioxide water purification - see www.katadyn.com/usen/
  "Katadyn offers a wide variety of water filtration and purification products suitable for any need. This allows outdoor enthusiasts and travelers to take along products for making their own drinking water when preparing their trips."
• Arlene Puentes, a licensed home inspector, educator, and building failures researcher in Kingston, NY. 11/29/06
• Wilderness Medical Society has advice about boiling water for consumption
• Princeton University - www.princeton.edu
• "Bacteria in Drinking Water" - "Chlorine," Karen Mancl, water quality specialist, Agricultural Engineering, Ohio State University Extension. Mancl explains factors affecting the effectiveness of chlorine in water as a means to destroy bacteria and other microorganisms. OSU reports as follows:

  Chlorine kills bacteria, including disease-causing organisms and the nuisance organism, iron bacteria. However, low levels of chlorine, normally used to disinfect water, are not an effective treatment for giardia cysts. A chlorine level of over 10 mg/1 must be maintained for at least 30 minutes to kill giardia cysts. -- http://ohioline.osu.edu/b795/index.html is the front page of this bulletin.

• Crystal Clear Supply provides portable ceramic water filter purifiers and portable reverse osmosis water treatment equipment - see http://www.crystalclearsupply.com/category_s/7.htm
• "Do Iodine Water Purification Tablets Provide an Effective Barrier against Cryptosporidium parvum?", Starke, Jeffrey A., Bowman, Dwight D., Labare, Michael, Fogarty, Elizabeth A., and others, Military Medicine, 25 October 2001 [possibly a later version of this article appeared in 2005 -DF] http://www.amsus.org/military medicine/milmed.htm
• "Drinking Water Safety in Emergencies", University of Minnesota extension, extension.umn.edu/info-u/nutrition/BJ646.html
• FDA Warning about drinking hydrogen peroxide: www.truthorfiction.com/rumors/h/hydrogen-peroxide.htm This article cites a 2003 entry in Journal of Food and Science on using Hy.Perox to sterilize vegetables, referring to E.coli - NOT to Giardia.
• www.epa.gov/ogwdw/mdbp/pdf/alter/chapt_2.pdf provides an article on use of disinfectants for water treatmen
• This patent application for UV light sterilization www.patentstorm.us/patents/6565803.html Lists good references on water purification for Giardia et als
• Giardia exposure limits for drinking water: see www.mass.gov/dep/water/drinking/standards/giardia.htm is the current regulatory exposure limit (your minimum target for sterilization)
• Wikipedia on history of use of hydrogen peroxide: Information on Hydrogen peroxide as a sterilant is in Wikipedia at en.wikipedia.org/wiki/Sterilization_(microbiology) HO2 has been used for a long time, including by vaporization for sterilizing freeze dryers.
• 1-Bromo-3-chloro-5,5-dimethylhydantoin (C5H6BrClN2O2) is produced world-wide and is also used in cleaners and bathroom disinfectants and deodorizers. Here is an example MSDS for this product, provided by Leisure Time

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• Potable Aqua® emergency drinking water germicidal tablets are produced by the Wisconsin Pharmacal Co., Jackson WI 53037. 800-558-6614 pharmacalway.com
• Principles and Practice of Disinfection, Preservation and Sterilization (Hardcover)
  by A. D. Russell (Editor), W. B. Hugo (Editor), G. A. J. Ayliffe (Editor), Blackwell Science, 2004. ISBN-10: 1405101997, ISBN-13: 978-1405101998.
  "This superb book is the best of its kind available and one that will undoubtedly be useful, if not essential, to workers in a variety of industries. Thirty-one distinguished specialists deal comprehensively with the subject matter indicated by the title ... The book is produced with care, is very readable with useful selected references at the end of each chapter and an excellent index. It is an essential source book for everyone interested in this field. For pharmacy undergraduates, it will complement the excellent text on pharmaceutical microbiology by two of the present editors."
  The Pharmaceutical Journal: "This is an excellent book. It deals comprehensively and authoritatively with its subject with contributions from 31 distinguished specialists. There is a great deal to interest all those involved in hospital infection ... This book is exceptionally well laid out. There are well chosen references for each chapter and an excellent index. It is highly recommended." The Journal of Hospital Infection.: "The editors and authors must be congratulated for this excellent treatise on nonantibiotic antimicrobial measures in hospitals and industry ... The publication is highly recommended to hospital and research personnel, especially to clinical microbiologists, infection-control and environmental-safety specialists, pharmacists, and dieticians."
  New England Journal of Medicine: City Hospital, Birmingham, UK. Covers the many methods of the elimination or prevention of microbial growth. Provides an historical overview, descriptions of the types of antimicrobial agents, factors affecting efficacy, evaluation methods, and types of resistance. Features sterilization methods, and more. Previous edition: c1999. DNLM: Sterilization--methods.
• Handbook of Disinfectants and Antiseptics, Joseph M. Ascenzi (Editor), CRC, 1995, ISBN-10: 0824795245 ISBN-13: 978-0824795245 "The evaluation of chemical germicides predates the golden age of microbiology..." -
  This well-focused, up-to-date reference details the current medical uses of antiseptics and disinfectants -- particularly in the control of hospital-acquired infections -- presenting methods for evaluating products to obtain regulatory approval and examining chemical, physical, and microbiological properties as well as the toxicology of the most widely used commercial chemicals.
• When Technology Fails, Matthew Stein, Chelsea Green Publisher, 2008,493 pages. ISBN-10: 1933392452 ISBN-13: 978-1933392455, "... how to find and sterilize water in the face of utility failure, as well as practical information for dealing with water-quality issues even when the public tap water is still flowing". Mr. Stein's website is www.whentechfails.com/

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