Total Coliform - Testing Water for Bacterial Contaminants
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What is Total Coliform ?
Why do we test water for Coliform bacteria?
When do we test for fecal Coliform ? Escherichia coli / E. coli
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This article gives advice on testing water for bacterial contamination using the total coliform test - Scott Bradley, Aquacheck.
Also see these articles about water tests for bacterial or microbial contamination:
Water Potability Tests - "Bacteria" tests or Microbial Contamiantion Tests
Total Coliform or T-colibacteria testing indicates a total count or measure of the level of coliform bacteria in a water sample.
If water "fails" a T-coli test, further testing is needed. Because not all coliform bacteria are cause for "failing" a water potability test, if a water test result discloses high or excessive T-coli alone, what we can conclude is that further investigation is needed.
If the water test passes a T-coli test as not detected, absent, or below your community's acceptable minimum level, the water is considered safe to drink insofar as bacterial contamination is concerned. Of course other contaminants (chemicals, for example) could still be present in such a water sample.
Escherichia coli (EC or E-coli) bacteria tests in water indicate the presence of (or depending on the test performed, the count or level of colony forming units of) Escherichia coli.
If water "faIls" an E-coli test, the water is not safe to drink. Escherichia coli is a specific indicator of the presence of humanh or animal fecal waste contamiantion of the water supply, a water test which detects an unacceptable level of Escherichia coli is unsafe to drink. The source of contamination needs to be found and corrected or if this is not possible, an appropriate water treatment system is installed.
As we suggested above for T-coli, if the water test passes an E-coli test as not detected, absent, or below your community's acceptable minimum level, the water is considered safe to drink insofar as bacterial contamination is concerned. Furthermore, T-coli may be present and E-coli absent and the water test may be considered acceptable. However in our OPINION, a high T-coli water test
Of course other contaminants (chemicals, for example) could still be present in such a water sample.
HPC heterotrophic plate count in water test results: aerobic and facultative aerobic bacteria are both detected by the HPC count.
The HPC count is not part of most basic water potability tests. You may order this test, for example, as part of diagnosing a known or suspected problem, or to help check for growth of microbial contaminants in treated water. HPC or the heterotrophic plate count, along with total coliforms (T-coli) and Escherichia coliform (E-coli) counts are used to indicate the level of microbiological contamiantion of water tests for potability.
For more information about the use of HPC testing of drinking water see this World Health Organization paper: The History and Use of HPC in Drinking-Water Quality Management (web searhc 02/10/2011, original source http://www.who.int/water_sanitation_health/dwq/HPC3.pdf)
A basic water "bacteria test" may or may not be equally sensitive to all three of these data, and not all water tests or water test labs report all three of these individual measures.
Watch out: even if your water sample passes a coliform test, bacteria test, or T-coli or E-coli test, that does not guarantee that there are no chemical contaminants in the water supply.
Not all water bacteria tests are the same. See these articles about water tests for bacterial or microbial contamination:
Details about Total Coliform Bacteria Information for Homeowners
The photos shown here illustrate the simple and inexpensive Total Coliform Test procedure.
When the reagent is added to a properly-collected
water sample, the liquid remains clear (left hand photo) if the total Coliform count in the sample is less than 1 colony-forming-unit or 1cfu/100ml and turns yellow (right hand photo) if the total Coliform count
is above 1 cfu/100ml of water in the water test sample.
What are "Total Coliform Bacteria" and why test for them?
What exactly are Total Coliform bacteria and why do we test for them in our drinking water?
Total Coliform bacteria are part of a family of bacteria called, Enterobacteriaciae, or Enterics, for short.
Coliform bacteria have some interesting characteristics that allow us to use them as indicator organisms.
In this case, a Coliform present sample in drinking water indicates that the source is, or recently has been infiltrated by surface water.
[Coliform bacteria are almost always present in surface water.]
We use "Coliforms" to help us determine this, because Coliform bacteria are found throughout the environment, as well as on most plant material.
They live longer than the pathogenic (disease-causing) microbes we don't want you to get, so it allows us to culture them in the lab.
Finding Coliform bacteria in a drinking water sample does not mean anyone is going to become ill. After personally analyzing over fifty thousand individual Coliform tests, we wish we had a nickel every time someone would say to me something like, "I've been drinking' this water for over
seventy years, and we never been sick from it once!" While that may be all well and true, drinking water that contains certain contaminants has been one of the leading causes of major disease outbreaks, historically speaking.
Will Coliform bacteria in water make you sick?
When we find Coliform bacteria in your drinking water sample, as stated above, it simply indicates that the source is, or recently has been compromised by surface water.
We're not so concerned about the Coliform bacteria themselves, but the "red flag" if you will, is that we don't know what else may have gotten in your drinking water system via the same route that the Coliform bacteria entered. Some types of bad microbes we don't want you to ingest, for example, would be Klebsiella, Shigella, Cryptosporidium, Giardia, or Salmonella, just to name a pesky few!
Most drilled wells are free from Coliform bacteria, but many dug wells contain Coliform. This is not surprising, since dug wells are a surface water source, which means it is above the bedrock layer.
Dug wells, can be an excellent source of drinking water, but extra care should be taken to be sure there is adequate separation from the well with respect to pets, farm animals, and runoff.
If you have a dug well, the volume and taste are fine, but it keeps getting Coliform bacteria, then a viable and effective option may be to install an ultraviolet disinfection system, which kills the bacteria and other microbes by separating, or denaturing the DNA or RNA of their cells.
This works well because it doesn't change the chemistry of the water like some other disinfection methods, such as chlorination.
However any water treatment system requires care and monitoring, lest you think it's working when it's not. Further, the presence of surface water in your water supply might mean that other surface contaminants, such as chemicals, are
also present. If this is the case, a UV-light is not going to remove them. This is why further testing of your water may be in order before deciding just what water treatment system should be installed.
Finally, if Total Coliform bacteria is found in a drinking water sample, then the sample is also checked for a type of
fecal Coliform bacteria, which is always Escherichia coli, or E. coli. The presence of E. coli may mean a septic or leach field infiltration, or in a dug well, it just may be a squirrel
or field mouse that tried to make his home in your well! We'll cover well disinfection in another session.
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Scott Bradley, author. Scott Bradley is Laboratory Director for Aquacheck Laboratory, Inc. PO Box 87 05151 1-800-263-9596.
This article appeared in Aquacheck Laboratory's
Water Wisdom Tips and Newsletter, Issue # 1,
www.Aquacheck-VT.com offers other water supply tips in its Water Wisdom section.
The laboratory also provides water test kits and offers a free newsletter.
Thanks to
Don Salter,
Leuther Laboratories, Coon Valley, WI for close editing and correction to our use of the full name for E. coli: it is Escherichia coli not Escherichia coliform! August 2008.
The History and Use of HPC in Drinking-Water Quality Management, WHO, World Health Organization, Regional Office of the World Health Organization
525 Twenty-third Street, N.W., Washington, D.C. 20037, United States of America, Country/City Code: (202) Tel: 974-3000 Fax: 974-3663, Email: info@who.int. web search 02/10/2011, original source: http://www.who.int/water_sanitation_health/dwq/HPC3.pdf
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Access Water Energy, PO Box 2061, Moorabbin, VIC 3189, Australia, Tel: 1300 797 758, email: sales@accesswater.com.au Moorabbin Office: Kingston Trade Centre, 100 Cochranes Rd, Moorabbin, VIC 3189
Australian supplier of: Greywater systems, Solar power to grid packages, Edwards solar systems, Vulcan compact solar systems, water & solar system pumps & controls, and a wide rage of above ground & under ground water storage tanks: concrete, steel, plastic, modular, and bladder storage tanks.
Cheating on water tests: Testing Water for Real Estate Transactions - make sure your water test is valid
Smart Tank, Installation Instructions [ copy on file as /water/Smart_Tank_Flexcon.pdf ] - , Flexcon Industries, 300 Pond St., Randolph MA 02368, www.flexconind.com, Tel: 800-527-0030 - web search 07/24/2010, original source: http://www.flexconind.com/pdf/st_install.pdf
Typical Shallow Well One Line Jet Pump Installation [ copy on file as /water/Jet_Pump_Grove_Elect_Jet_Pumps_1.pdf ] - , Grove Electric, G&G Electric & Plumbing, 1900 NE 78th St., Suite 101, Vancouver WA 98665 www.grovelectric.com - web search -7/15/2010 original source: http://www.groverelectric.com/howto/38_Typical%20Jet%20Pump%20Installation.pdf
Typical Deep Well Two Line Jet Pump Installation [ copy on file as /water/Jet_Pump_Grove_Elect.pdf ] - , Grove Electric, G&G Electric & Plumbing, 1900 NE 78th St., Suite 101, Vancouver WA 98665 www.grovelectric.com - web search -7/15/2010 original source: http://www.groverelectric.com/howto/38_Typical%20Jet%20Pump%20Installation.pdf
Water Fact Sheet #3, Using Low-Yielding Wells [ copy on file as /water/Low_Yield_Wells_Penn_State.pdf ] - , Penn State College of Agricultural Sciences, Cooperative Extension, School of Forest Resources, web search 07/24/2010, original source: http://pubs.cas.psu.edu/FreePubs/pdfs/XH0002.pdf
Water pressure tanks - how to diagnose the need for air, how to add air, stop water pump short cycling to avoid damage - water storage water pressure tank safety.
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The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop, and from the InspectAPedia bookstore. The 2010 edition of the Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
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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.
"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.
U.S. Army Field Manual 21-10, Field Hygiene and Sanitation, 1988, web search 07/02/2010, original source: http://www.enlisted.info/field-manuals/fm-21-10-field-hygiene-and-sanitation.shtml The purpose of this manual is to assist individual soldiers, unit commanders, leaders and field sanitation teams in preventing disease and environmental injuries. The manual provides information on preventive medicine measures (PMM) to the individual soldier as well as essential information for the unit commander, unit leaders, and the unit field sanitation team on applying unit level PMM.
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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Total Coliform - Testing Water for Bacterial Contaminants
