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How to Purify or Sterilize Drinking Water for Emergency Use After a Flood, Fire, or Earthquake Disaster MoldAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• How to treat, purify, or sterilize drinking water in an emergency
• How to use bleach, boiling, chlorine, distillation, filters, hydrogen peroxide, iodine tablets, or iodine liquid to purify drinking water
• How to get rid of chlorine odors or other chemical odors in emergency drinking water supplies

This article 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.

Flood Response Checklist lists key actions you should take after building flooding to minimize mold damage, and includes some safety warnings. Before entering a building that has been affected by a disaster such as fire, earthquake, or flood, see BUILDING ENTRY PROCEDURE for some safety warnings for occupants, building owners, or volunteers who may find themselves indoors in a disaster area and without immediate assistance from rescue workers or other experts.

© Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

How to Treat or Purify Water to Sanitize it For Drinking

Beware that most advice about purifying water, including the tips we have collected below, address biological contaminants in water, such as bacteria.

Health Warnings about Effective Water Purification

• Chemical contaminants: If your water supply has become contaminated by pesticides, heavy metals, or other chemicals, disinfecting the water will not correct those unsafe conditions.
• Protozoan contaminants: Chlorine and iodine are good disinfectants against bacterial contamination (probably among the most common water contaminants) but studies have shown that these are not effective against certain contaminants in water such as toxic chemicals, Cryptosporidia (Cryptosporidium parvum) , and Giardia.
• Filtration and boiling are additional steps that can address these microorganisms. Activated charcoal can remove some chemical contaminants but has limited life and capacity.

The principal methods used to purify water when camping or in an emergency include:

• Boil the water
• Use chlorine (bleach, sodium hypochlorite) to purify the water. (see warnings just above)
• Use iodine tablets or a liquid tincture of iodine to purify the water for emergency use (see warnings just above)
• Use a filter designed for water purification, particularly ceramic filters and silver-ceramic filters
• Use a water purifying pump such as models sold by camping equipment suppliers to purify the water
• Use a water distiller such as a home or portable distillation unit (our photo shows a Sears® home water distiller)
• Use a reverse osmosis water filtration system if water pressure is available or if a portable R.O. system is available.

Basic water purification procedures that can be used in an emergency are described just below. If community or private wells are back in operating and providing water, do not assume that the water is sanitary and ok to drink until responsible authorities have said so. Even then, local water pipes in a building may be unsanitary and additional cleaning or disinfection may be needed. See WELL CHLORINATION SHOCKING PROCEDURE and see WATER TESTS, CONTAMINANTS, TREATMENT for advice on using a private well for drinking water.

Boiling water to purify it:

If drinking water is of questionable purity, boil the water for at least five minutes, and/or add bleach, and/or distill drinking water before using if a distiller and electrical power or an alternative heat source are available. See information on water treatment under the "Disaster Supplies Kit" section of some public documents.

In most environments, the length of time that water is exposed to temperatures of 185 degF. or higher between the time it reaches 185 degF. and the time that it reaches boiling at 212 degF. is sufficient to kill most organisms and pathogens in the water. That's why experts have not suggested that you need to boil the water for more than a minute or so. If you are boiling water on an unusually hot powerful heat source, boil it a bit longer to be safe.

Using Iodine or bleach or hydrogen peroxide to purify water:

Iodine and bleach (chlorine or sodium hypochlorite) are the two common ways to sterilize water chemically to address bacterial contaminants. Iodine tablets have been shown to be effective against Giardia muris but iodine tablets are not effective against Cryptosporidium species.

• Camping suppliers and other sources also can provide iodine tablets (or other chemical tablets) that can be mixed with a specified quantity of water to produce potable drinking water. Potable Aqua iodine water purification tablets are available from camping suppliers and other sources and are an inexpensive means of treating small volumes of emergency drinking water.
• If you have no iodine tablets but have liquid iodine such as would be used to treat a wound, (typically this is a 2% tincture of iodine) try a teaspoon of iodine in a gallon of water.
• Do not use iodine to purify water for certain people:
  • people who are allergic to iodine - possibly including people allergic to shellfish
  • people who have a thyroid disorder
  • people who are taking lithium (a medication)
  • women over fifty and women who are pregnant (without a doctor's advice)
• Iodine alternatives for disinfectants include chlorine-based products (bleach) and non-iodine-based water filters
• Hydrogen peroxide may also be used to purify water, and its odor will dissipate rapidly.
• Vegetable disinfecting wash chemicals sold at many produce stores or grocery stores (Sin Bac, for example) often contain a chemical 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.

[OPINION] In an emergency if you have nothing else, no way to boil water, no ceramic filter, but you have iodine, use it. But beware that iodine is not fully effective as a water sterilization method.

Wait time & water temperature when adding a disinfectant, before drinking water:

• Typical wait time before drinking treated water is at least 30 minutes from the time that the treatment tablet has become fully dissolved in the water. The necessary time could be longer.
• Water temperature should be 65 degF or higher before treatment with bleach for best results. You may be able to warm your water by placing it in the sun. If the water is below 40 deg.F. you should double the wait time before consuming it.
• Water temperature should be 68 degF or higher before treating it with iodine. Iodine is more effective than bleach in killing off Giardia contamination in water.
• Be sure to read the instructions. Iodine, bleach (sodium hypochlorite), or other water disinfectants will require some wait time to permit the chemical to act on water bacteria before the water can be consumed.
• Using any chemical to sterilize water will require sufficient contact time between the chemical and the water before the water can be consumed.
• The chemical, bleach, or iodine, needs time to kill the microorganisms in the water.
• If you have iodine tablets intended for purifying water, the tablet bottle label should indicate the number of tablets to use per gallon of water and also the length of time that you must let the water sit before drinking it.
• If using liquid iodine to purify water, let the treated water sit for a day before using it to drink.
• If your water supply is very cold you will need to increase the wait time for the chemical disinfectant to act before the water can be consumed.
• If your water supply is cloudy you will need to increase the wait time for the chemical disinfectant to act before the water can be consumed. That's why experts recommend filtering the water with a clean cloth first if you can. In an emergency you might also be able to use clean coffee filters or even plain white paper towels.

How much disinfectant to use in drinking water?:

The amount of disinfectant needed to purify water depends on how contaminated the water is to begin with. If you are using liquid iodine and have no better authoritative information, try a teaspoon of iodine per gallon of water. Other experts recommend:

• 5 drops of 2% tincture of iodine per quart of clear water
• 10 drops of 2% tincture of iodine per quart of cloudy water
• Other water disinfectant products based on iodine: the label will indicate the number of capfuls of disinfectant to use per quart of water
• Iodine tablets, such as PotableAqua™ - (50 tablets per bottle) two tablets treats a quart of water and are effective against Giardia lambia.

Filter the drinking water for Purification:

The best procedure if you don't know much about the water condition is to filter it before and after it is treated with bleach, chlorine, iodine, or other sterilization methods.

Ceramic water purifying filters:

Purifying filters use materials such as ceramic filters which have extremely fine pores to filter out harmful bacteria and protozoa.

Portable ceramic water filters all include a pump, usually a manual or hand pump, which forces water through a very fine ceramic filter cartridge, delivering a clean, if slow stream of potable drinking water. Some portable ceramic water filters include a container into which water is poured, then pumped out. Other ceramic water filter systems such as a model we used during weeks of rafting down the Colorado River, are intended to deliver a larger quantity of potable water: these models can be inserted into a larger container of water. The hand pump draws water out of the container, through the filter, and then delivers it out of a spout or tube into a clean container for drinking or other uses.

Examples of portable ceramic water filters include the Katadyn® ceramic water filter, Hiker Pro Micro Filter (also from Katadyn), and ExsStream ceramic water filter.

In the event that the municipal water supply system is working after a hurricane, flood, or other disaster, companies like Katadyn also produce water filters that can be attached to a faucet and are operated by system water pressure.

Doulton® is a company in the U.K. with branches in the U.S. that produces a wide range of ceramic water filtration equipment including point of use filters (POU filters) and filters that can operate by gravity rather than requiring a pump. A gravity operated ceramic water filter would be an effective means of sanitizing water from a rooftop water cistern.

Small portable water filters are produced by Pure Water 2Go®, and MSR MiniWorks® Water Filter. Small and larger capacity portable ceramic water filters are available from many sources including camping equipment suppliers and water treatment equipment suppliers such as Crystal Clear Supply.

Silver ceramic water filters are ceramic water filters which have been treated with colloidal silver - a step which increases filter effectiveness by killing bacteria in water passing through the system.

Sink cartridge water filters: We would not rely on the smaller store-bought filter cartridges that are simply attached to the tip of a kitchen sink faucet without clear documentation about just what that filter cartridge can remove from water, and how many of gallons of water it can process before it is exhausted. It would be unsafe to continue to "purify" water through an exhausted cartridge like filter. In contrast, ceramic water filters have a very high gallon capacity and most models can simply be cleaned and re-used.

Reverse osmosis [OPINION] also removes contaminants from water; however in an emergency where public water supplies and/or electrical power are not provided, we do not assume that a home or building reverse osmosis system will be functional.

However, portable reverse osmosis water treatment equipment is available from companies such as Crystal Clear Supply.

Charcoal water filters [OPINION] are often used as a step in water treatment systems, combined with a chlorination system. A standalone charcoal filter for portable temporary water purification risks becoming contaminated with bacteria.

UV Lights [OPINION] are installed in some properties as a means to kill bacteria in a water supply. We do not anticipate that UV light systems will be working in a disaster area, and we are doubtful that one can rely on this process for emergency drinking water purification: even if a UV light system is working, it will at best kill bacteria and similar pathogens only. It will not remove chemical contaminants in a water supply.

Because we figure that it's unlikely that most people will have a ceramic filter on hand after a hurricane, flood, or earthquake we have not (yet) put those details in this article.

Magnetic water filters and purifiers: [OPINION] are junk science and are not a reliable means of assuring safe drinking water.

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.

Advice If Using a Garden hose to collect water?

Do not collect water from a water heater, water pressure tank, or rooftop tank by using a garden hose that was contaminated by floodwaters unless the hose has been properly cleaned and disinfected.

Building Flood Damage, Cleanup, and Mold Prevention Articles (Green Links shows where you are)

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP A Guide to Mold Cleanup Procedures
  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
  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

Technical Reviewers & References

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Daniel Friedman - principal author/editor of the InspectAPedia ^TM Website
• 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
• 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
• Technical reviewers are invited to comment or ask questions - contact us

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