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Sanitary water may be found in closed containers (C) Daniel FriedmanDisinfect or "Purify" Water using Bleach
Chlorine, or Other Disinfectants to Purify or Sterilize Drinking Water

This article describes 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.

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How to Use 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.

Drops of Bleach to Be Added to a One Quart Container For Emergency Drinking Water
Available Chlorine in the Bleach Solution
Drops of Bleach to Use per Quart of Clear Water
Drops of Bleach to Use per Quart of Cold or Cloudy Water
1%
10
20

4—6% 

(This is typical household bleachor laundry bleach)

2
4
7--10%
1
2

 

Notes to the table above

Watch out: do not confuse the much lower concentration of bleach used when preparing emergency drinking water with the higher concentration of disinfectant needed to disinfect water wells or water treatment equipment

Detailed advice are on this page and more information is at

WATER TREATMENT EQUIPMENT DISINFECTION

WELL CHLORINATION & DISINFECTION

Bleach disinfection of Emergency Drinking Water

If you are preparing emergency drinking water because your water well has been contaminated by flooding, the well cannot be repaired for safe use until flood waters have resided.

See WELL DISINFECTION PROCEDURE, POST FLOODING

In our detailed drinking water chlorination procedure article found

at WATER DISINFECTANT QUANTITY we review again the amount of bleach and also the quantity of other disinfectants needed in more detail and we describe the U.S. EPA's advice for superchlorination of drinking water.

Watch out: Bleach will not kill Giardia in typical drinking water disinfection methods such as those discussed here.

While chlorine can kill Giardia cysts if used in high enough concentration and for sufficient contact time, 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.

In a more complete set of warnings about relying on disinfection to provide safe drinking water given
at WATER DISINFECTION LIMITATIONS we report that relying on disinfectant to kill Cryptosporidium cysts is a mistake too.

Katadyne Micropur chlorine dioxide kit Cryptosporidium cysts might even survive a typical municipal chlorine disinfection process (such as at a municipal water treatment plant).

[Click to enlarge any image]

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.

Watch out: for these limitations on the effectiveness of bleach or chlorine disinfection of drinking water or grey water:

Vegetable Disinfection Washes & Treatments

This discussion has been moved to a separate article: VEGETABLE or PRODUCE DISINFECTION


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Continue reading at WATER DISINFECTANT QUANTITY or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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BLEACH DISINFECTANT for DRINKING WATER at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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INDEX to RELATED ARTICLES: ARTICLE INDEX to WATER TREATMENT SYSTEMS

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