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Well depths and types (C) Carson Dunlop AssociatesWell Disinfectant Choices

Well disinfectant chemicals & their properties:

This article describes the properties of three most common disinfectants used to shock or sanitize a water well: chlorine (common household bleach), chloramine, and chlorine dioxide.

Page top sketch illustrating both deep and shallow water well construction and depths is provided courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

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Comparison of the 3 Common Well Water Disinfectants: Chloramine, Chlorine and Chlorine Dioxide

Chloramine, Chlorine and Chlorine Dioxide Used for Well Shocking / Disinfection Procedures
Disinfectant Common Usages Health Effects Comments
Chloramine (as Cl2)

Chloramine is a water additive used to control microbes ... as a residual disinfectant in drinking water distribution system pipes.

Chloramine is formed when ammonia is added to water containing free chlorine. Monochloramine is a form of chloramine commonly used for disinfection by municipal water systems

 Drinking water with excessive levels of chloramine above the maximum residual disinfectant level (MRDL) could experience irritating effects to their eyes and nose, stomach discomfort or anemia MRDL = 4.0 mg/L or 4 ppm as an annual average
Chlorine (as Cl2)

As a gaseous or liquid form of chlorine (CL2) chlorine is a powerful oxidant used by municipal water systems to control microbes.

Chlorine is relatively inexpensive and has the lowest production and operating costs and longest history for large continuous disinfection operations.

Some people who use water containing chlorine well in excess of the maximum residual disinfectant level could experience irritating effects to their eyes and nose.

Some people who drink water containing chlorine well in excess of the maximum residual disinfectant level could experience stomach discomfort.

 MRDL = 4.0 mg/L or 4 ppm as an annual average
Chlorine dioxide (as ClO2) Chlorine dioxide is added to water to control microbes and can be used to control tastes and odors. Highly volatile, chlorine dioxide rapidly disappears from stored water.

Some infants, young children, and fetuses of pregnant women who drink water containing chlorine dioxide in excess of the maximum residual disinfectant level could experience nervous system effects

. Some people who drink water containing chlorine dioxide well in excess of the MRDL for many years may experience anemia.

 MRDL = 0.8 mg/L or 800 ppb
Household Bleach e.g. Clorox® contents & purposes of each chemical
  1. Sodium hypochlorite (NaClO)
  2. Sodium chloride (NaCl)
  3. Sodium carbonate (Na2CO3)
  4. Sodium chlorate (NaClO3)
  5. Sodium hydroxide (NaOH)
  6. Sodium polyacrylate (C3H3NaO2)n
  7. Water (H2O)
  1. In Clorox's EPA-registered disinfecting and sanitizing products, sodium hypochlorite is the active ingredient that helps to kill certain germs. This is the principal ingredient in household bleach.
  2. Sodium chloride (table salt) is used as a thickener in some products.
  3. Sodium carbonate (washing soda) is an alkalinity builder that boosts the cleaning power of laundry detergents
  4. Sodium chlorate is an intermediate product in the break-down of standard bleach (sodium hypochlorite); it further breaks down into sodium chloride (salt) and oxygen.
  5. Sodium hydroxide (lye, caustic soda) is used to adjust the pH of cleaners and to assist in breakdown of fats & oils
  6. Sodium polyacrylate helps keep soils suspended during washing to avoid re depositing them on fabrics being cleaned.

According to the US ATSDR's fact sheet on chlorine:

Watch out: Drinking small amounts of hypochlorite solution (less than a cup) can produce irritation of the esophagus.

Drinking concentrated hypochlorite solution can produce severe damage to the upper digestive tract and even death. These effects are most likely caused by the caustic nature of the hypochlorite solution and not from exposure to molecular chlorine.

Spilling hypochlorite solution on the skin can produce irritation. The severity of the effects depends on the concentration of sodium hypochlorite in the bleach.

Adapted from clorox.com

For emergency disinfection of drinking water (his is NOT the same thing as disinfecting a well) add 8 drops of Clorox bleach to a gallon of clear water, (or just two drops to a quart) and let the solution stand for at least 15 minutes (a very slight "bleach" odor should remain.

If there is no bleach odor the water may not be adequately disinfected.

See DRINKING WATER EMERGENCY PURIFICATION

See CHLORINE HAZARDS in WATER

Notes to the table above

The above information is adapted from US EPA, Water: Basic Information about Regulated Drinking Water Contaminants, retrieved 8/27/2013, original source water.epa.gov/drink/contaminants/basicinformation/disinfectants.cfm [1]
and from information provided by clorox.com

Watch out: The US EPA recommends that you test your water every year for total coliform bacteria, nitrates, total
dissolved solids, and pH levels.

If a review of local well water contaminants found by local testing labs, your local health department, or other information about your particular property suggests that there is a risk of other chemical contaminants (such as agricultural chemicals, pesticides, or local chemical spills or dumps) then you should include a test for these contaminants as well.

For problem wells whose contamination is not easily cured by the above, see WELL DISINFECTANT TABLE, POST FLOODING

...

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Citations & Reviewers

In addition to any citations in the article above, a full list is available on request.

  • [1]US EPA, "Water: Basic Information about Regulated Drinking Water Contaminants", retrieved 8/27/2013, original source http://water.epa.gov/drink/contaminants/basicinformation/disinfectants.cfm
  • [1a] Drinking Water from Household Wells - PDF, U.S. EPA, Original source last retrieved 2/13/2013, original source: http://www.epa.gov/privatewells/pdfs/household_wells.pdf
  • [1b] US EPA, "Chlorine Dioxide" (Alternative Water Disinfectants Manual) [PDF] U.S. Environmental Protection Agency
  • [2] ATSDR Agency for Toxic Substances Disease Registry, Toxic Substances Portal: Chlorine Toxicity, [PDF] November 2010, retrieved 8/27/2013, original source: www.atsdr.cdc.gov
  • [2a]Thanks to reader Jerry Highsmith for discussing well shocking procedures where a water filter or water softener are installed - August 2010
  • [3] "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.

  • [5] Canadian BC Ministry of Environment, "Water Stewardship Information Series: When Standard Water Well Chlorination Procedures are Ineffective Fact Sheet developed for Well Drillers, Health Authority Staff and others involved in well recovery efforts after a flood " ", Agriculture and Agri-Food, Canada, retrieved 4/8/2013 original source: http://www.env.gov.bc.ca/wsd/plan_protect_sustain/ groundwater/wells/factsheets/PFRA_well_recovery.pdf
  • [5a] "Chemical Cleaning, Disinfection and Decontamination of Water Well" John Schnieders. Johnson Screens Inc. St. Paul, MN
  • [5b] Water Well Management Level 2 Training Module. Prairie Farm Rehabilitation Administration of Agriculture and Agri-Food Canada, Alberta Environment, Alberta Water Well Drilling Association and Alberta Agriculture, Food and Rural Development
  • [6] Water Wells that last for Generations. Alberta Agriculture, Food and Rural Development; Alberta Environment; Prairie Farm Rehabilitation Administration of Agriculture and Agri-Food Canada
  • [7] Water Well Management Level 2 Training Module. Prairie Farm Rehabilitation Administration of Agriculture and Agri-Food Canada, Alberta Environment, Alberta Water Well Drilling Association and Alberta Agriculture, Food and Rural Development
  • [8] Chemical Cleaning, Disinfection and Decontamination of Water Wells. John Schnieders. Published by Johnson Screens Inc. St. Paul, MN
  • Ohio State University article on the concentration of chlorine necessary to act as an effective disinfectant, and the effects of the water's pH and temperature: See http://ohioline.osu.edu/b795/b795_7.html for details.
  • Water Quality Association P.O. Box 606 4151 Naperville Road Lisle, IL 60532 www.wqa.org
  • National Sanitation Foundation P.O. Box 130140 789 N Dixboro Road Ann Arbor, MI 48113-0140 (734) 769-8010, (800) NSF-MARK www.nsf.org
  • U.S. Environmental Protection Agency (to visit in person) Office of Water Resource Center 1200 Pennsylvania Avenue, NW Ariel Rios Building Washington, DC 20460 Phone: (202) 260-7786, email: center.water-resource@epa.gov
  • The Safe Drinking Water Hotline (800) 426-4791 The hotline operates from 9:00 AM to 5:30 PM (EST) The hotline can be accessed on the Internet at www.epa.gov/safewater/drinklink.html
  • Water Systems Council www.watersystemscouncil.org
  • Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
  • 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
  • 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.
  • 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.
  • In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested

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