This article gives advice on water testing for property or home buyers or home owners, with focus on a strategy for assuring the quality of well water by site inspection, property history investigation, and strategically-selected water tests for contamination.

Discussed here: Water potability testing guide - water bacteria test guide. Articles Describing Types of Water Potability Tests, Water Purity Tests, Test for Other Water Contaminants. How to conduct water tests, what water tests to order, how to avoid dishonest or cheating on water tests.

The articles listed on this water testing advice page will answer most questions about drinking water testing, focused on testing water supplied from wells, & water tanks as well as many other building plumbing system inspection or defect topics.

Water Testing Advice

How to Investigate for Water Contaminants at a New or Unknown Property or a Private Drinking Water Well

General advice on water testing when buying a rural property:

The minimum test for water potability elected by many property owners or buyers looks only at bacteria. Some government lenders require more extensive tests such as the FHA and Title-5 water potability testing series.

Those and similar "water test package" deals offered by water testing labs can be a good way to spend your water testing dollars as they test for the most common contaminants found in well water in many areas.

Watch out for "False Negative" assurances that Well Water is "Pure"

First of all, no water test assures against all possible contaminants in water.

Second, water tests that focus on water potability (is the water safe to drink) may miss other important water conditions, such as water that is too high in mineral content, clogging pipes and water heaters, or water that is too acidic or corrosive, causing leaks in copper piping.

See details about measuring water hardness and about corrosive or acid water at the Recommended Articles near the end of this page.

Watch out: even so, property buyers should beware of ordering water tests arbitrarily, Because of the enormous number of potential chemical contaminants that might show up in water, there is a risk of accepting a "false negative" result, that is, a risk of assuming that there are no contaminants in drinking water after a specific water contaminant tests shows a negative result.

It may simply be the case that a contaminant that is present was not detected because it was not within the scope of the tests performed.

Therefore to be more confident about the quality of water at a property whose water and land history may be unknown, we recommend a series of escalating steps in water testing and other investigative measures.

At several points in the investigation process a property buyer or new owner may decide that the information obtained so far provides enough confidence, or that the information suggests that additional levels of water testing are appropriate.

Site investigation for well water quality concerns

This important step in investigating well water quality includes

A visual inspection for things that might raise a red flag: evidence of chemical, fuel, or fertilizer storage on the property or nearby at sites that drain onto the property, nearby industry (industrial chemicals), nearby orchards (pesticides) or farms (fertilizers) whose land drained across or onto the property.

Among the most basic observations will be the location of the well and its proximity to septic system drainfields, barns, livestock pens, or farm chemical storage tanks or fuel tanks. And of course the type of well (dug, driven point, steel well casing) and depth also have implications for the probability of contamination by surface runoff or subsurface contaminants.

Investigation by asking neighbors, the local health department, and nearby water testing laboratories to determine if they know of specific water quality problems that have been discovered in the neighborhood. This step can sometimes provide surprising payoff such as questions by one of our clients whose Pawling NY well had tested as "OK" for several contaminants.

A neighbor pointed out that a paper company had for years dumped acetone and other waste chemicals in an empty field across the street from the client's well. Testing found unusual levels of acetone in the water - an uncommon contaminant as acetone is so volatile, and not something that anyone would have tested for without a clue from a helpful neighbor.

Professional investigation services are available from environmental inspection and testing firms who will research government data bases of known sources of water contamination, but watch out: such investigations may not disclose small local industries or contamination sources.

Some Community Drinking Water Wells May Also Be Contaminated

In the U.S. and most other countries community water supplies, often defined as serving 25 or more homes, must be tested and found to comply with national or federal drinking water standards.

In the U.S. "The Safe Drinking Water Act (SDWA) is the federal law that protects public drinking water supplies throughout the nation. Under the SDWA, EPA sets standards for drinking water quality and with its partners implements various technical and financial programs to ensure drinking water safety. " - original source: https://www.epa.gov/sdwa retrieved 2018/02/13

However recent studies reported both in professional journals and in the national press point out that local water companies frequently fail to meet federal safe drinking water standards.

Contaminants in community or municipal water supplies can vary from the infamous lead contamination of water supply in areas of Flint Michigan to other contaminants such as nitrates, arsenic, or pathogens. There may also be municipal drinking water contminants that are themselves a byproduct of the disinfection process used by the municipal water treatment facility.

In a new study published in the Proceedings of the National Academy of Sciences, researchers found that, since 1982, between 3 and 10 percent of the country’s water systems have been in violation of federal Safe Drinking Water Act health standards each year.

In 2015 alone, as many as 21 million Americans may have been exposed to unsafe drinking water. - Plumer, Brad, Nadja Popovich, " Here Are the Places That Struggle to Meet the Rules on Safe Drinking Water", The New York Times, 2018/02/12 original source: https://www.nytimes.com/2018/02/12/climate/drinking-water-safety.html retrieved 2018/02/13, with more citations atReferences or Citations .

Choosing Specific Water Test Lab Tests for Water Quality

Informed by step 1 above, the minimum water test that is performed is a bacteria test or "water potability test".

While the minimal "presence/absence" test is popular and inexpensive, the test gives a "go / no-go" result (there is or is not a coliform bacteria level at or above 1 colony forming unit (CFU) per 100 ml of water).

Keep in mind that no water test assures a zero level of bacteria in water nor do health regulations require it. A more costly water test for bacteria provides an actual count of the bacteria level found, if above certain thresholds - this is a much more useful test as it is diagnostic both before and after attempts to correct a bacteria problem.

Bacteria testing does not itself assure anything about the presence or absence of chemical contaminants or aesthetic contaminants (silt, odors, hardness) in well water.

But nevertheless, if a water test "fails" a bacteria test, because a common source of high bacterial levels in well water is the leakage of surface runoff into a well, that means that there is also a higher risk of the presence of other contaminants that might be found on the ground surface (pesticides, fertilizers).

Therefore even if a home owner/buyer decides to perform only the most minimal bacterial testing, the result can be a red flag that more thorough testing for other contaminants is in order.

Where a well is on or near farmland or orchards, water testing labs will often recommend one of two pesticide tests (depending on property age and whether or not it's appropriate to test for DDT or chlordane or newer pesticides, as well as tests that can detect common ingredients in fertilizers.

At a property in Dutchess County, NY, where we found a "permanently-parked" trailer that had been used by Terminix™ to store pesticides I was worried about possible storage leaks and thus pesticide contamination in the nearby well.

Tests for pesticides found that there was no contamination of the well nor of soil around the trailer. The pest control company had been careful.

But a subsequent investigation of the property's history disclosed that a metal plating shop had been present in one of the buildings on the site.

Tests found high levels of chromium contamination of soils, water, and even a nearby stream bed, resulting in a serious environmental contamination issue that involved the new property owner as well as local, state, and federal environmental officials.

Where the visual inspection or a study of the property history discovers specific potential sources of contamination, it makes sense to discuss these with the water test lab director to decide what tests are most useful to perform.

Watch out: this discussion has focused on well water quality - what is "in" the well water that may make it unsafe or unpalatable to drink. We also mention and refer readers to other important water conditions, such as water that is too high in mineral content, clogging pipes and water heaters An equally important question is "does the well provide enough water" - a topic discussed.

Water Contaminants, Water Tests & Test Parameters, Water Treatments

Best bet for getting help with water contaminationor water tests, treatments, cures: use the search box found near the top or bottom of any InspectApedia article.

• 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

• ARSENIC in WATER - arsenic contaminants in water may occur naturally in some soils
• BACTERIA LEVELS in WATER, INTERPRETATION - what do bacteria levels, counts, or presence/absence results mean in a water test?
• BACTERIA TEST GUIDE - tests the level of microbial ccontaminants in water.
  
  The basic "present/absent" or "P/A" test is the minimum water potability test required by many home mortgage lenders. Also see HPC Heterotrophic Plate Count and be sure to see these articles
  •   Common Water Tests for Bacteria
    
        PA - Coliform Bacteria Test
    
        M.F.T. - Coliform Bacteria Test
    
        MPN - Coliform Bacteria Test
    
    Each of these water tests for bacterial contamination has different advantages, disadvantages, and sensitiities.
• CHEATING on WATER TESTS: how people use bleach & well disinfectants to hide unsanitary wells or failed septic sytems. Testing Water for Real Estate Transactions - how to make sure your water test is valid
• CHEMICAL CONTAMINANTS in WATER
  
  
  • "Chemicals and Our Health", Nicholas D. Kristof, New York Times, 16 July 2009, p. 27. This outstanding editorial calls for improvements in public health policy to address phthalates and other environmental contaminants from common chemicals and products in everyday use. - DJ Friedman
• Chlorine in water:
  • "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 bulle
• CHLORINTATE / SHOCK a WELL, HOW TO - Procedure for Shocking a Well to (temporarily or maybe longer) "Correct" Bacterial Contamination
• CHLORINE IN DRINKING WATER - Does Chlorine in Drinking Water Harm the Septic Tank? - Septic Tank Cleaning Advice
• CHLORINE IN SEPTIC WASTEWATER - Septic Tank Maintenance: Chlorine in Septic Systems - Septic Tank Maintenance Advice
• CHLORINE TESTS, WATER - how to measure the level of chlorine in water
• CHLORAMINE DISINFECTANTS - other disinfectants used to treat drinking water, secondary disinfection. This article
  also
  discusses CHLORAMINE TESTS, WATER
• CHOICES of WATER TESTS & FEES, lists water test choices & typical water test costs or fees
• COMPREHENSIVE WATER TEST PARAMETERS
• COMPREHENSIVE + PESTICIDES WATER TEST list of water contaminant test parameters
• CONTAMINANT CLASSES, in WATER & links to home buyer advice about water testing, drinking
• CORRECT UNSATISFACTORY WATER - what to do when water fails a water test, when to do it, treatment alternatives, equipment, filters, etc.
• CORROSIVITY or ACIDITY of WATER - corrosive water risks leaky copper water pipes; the Langelier Saturation Index..
• COSTS of VARIOUS WATER TESTS example water test fee schedule
• Disinfectants in water: www.epa.gov/ogwdw/mdbp/pdf/alter/chapt_2.pdf provides an article on use of disinfectants for water treatment
• DE-ZINCIFICATION vs WATER CHEMISTRY - corrosion of brass pipes & fittings & faucets leads to leaks & failures.
• DRINKING WATER CONTAMINANT WATER LIMITS - what are the maximum allowed or limits on various contaminants found in drinking water. Health Effects of Chemical Contaminants in Drinking Water, US Environmental Protection Agency, others.
• DRINKING WATER CONTAMINATION & POLLUTION - How to Detect, Test, Correct, and Prevent Well Water Contamination - US EPA - Groundwater
• DRINKING WATER EMERGENCY PURIFICATION - home - methods for providing potable (drinkable) water in an emergency
  • "Drinking Water Safety in Emergencies", University of Minnesota extension, extension.umn.edu/info-u/nutrition/BJ646.html
• ENDOCRINE DISRUPTOR EXCHANGE, Dr. theo Colborn (also see Our Stolen Future). From that website: The Endocrine Disruption Exchange, Inc. is the only organization that focuses primarily on the human health and environmental problems caused by low-dose and/or ambient exposure to chemicals that interfere with development and function, called endocrine disruptors. ...
  
  TEDX's work focuses on the endocrine system, which is the exquisitely balanced system of glands and hormones that regulates such vital functions as body growth, response to stress, sexual development and behavior, production and utilization of insulin, rate of metabolism, intelligence and behavior.
  
  Hormones are chemicals such as insulin, thyroxin, estrogen, and testosterone that interact with specific target cells. The interactions occur through a number of mechanisms, the easiest of which to conceptualize is through a lock and key arrangement.
• Filters for water
  • 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
• FHA WATER TESTS REQUIRED - specific list of test paramaters for FHA mortgage borrowers
• 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)
• GENERAL CLASSES of WATER CONTAMINANTS considered for Comprehensive Water Testing
• GENERAL WATER TEST PARAMETERS - what things are tested for when you don't have a specific problem in mind?
• HARDNESS of WATER - water high in minerals, typically calcium or managanese, risk clogged pipes & water heaters
• HERBICIDE CONTAMINATION in WATER - water test parameters
• HPC Heterotrophic Plate Count Bacteria - also see BACTERIA TEST GUIDE.
• HYDROGEN PEROXIDE for WATER DISINFECTION - how to use HYDROGEN PEROXIDE to treat, purify, or sterilize drinking water in an emergency. What concentration of H₂0₂ hydrogen peroxide to use for drinking water disinfection? Health warning about drinking hydrogen peroxide
  
  
  • 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.
• Hydrogen Peroxide warning: US 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.
• IODINE: "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
• INDIVIDUAL WATER CONTAMINANT TESTS - microbiological, metals, general water chemistry, organics, radiological and lead tests for contaminants in drinking water
• LEAD CONTAMINATION in WATER, HOW to TEST
• LEAD CONTAMINATION in WATER, HOW TO REDUCE in Drinking Water: how to test & correction lead in drinking water
• LEAD CONTAMINATION - WATER SUPPLY PIPES, Lead Testing & Correcting Contamination from - Lead Pipe Problems/Advice
• LEAD LEACHING WARNINGS - lead leaching out of brass & lead-containing pipes, plumbing fittings, faucets, fixtures
• LEAD POISONING, EXTREME SYMPTOMSSuggested by Feb 2006 NY Times Article on Kosovo Roma Camps
• LEAD in WATER, ACTION GUIDE
• Nitrate level in water, identifies contamination from septic system effluent or possibly from nearby animal or livestock facilities or barns. See NITRATE / NITRITE TOXICITY ATSDR: [Big, Slow-Loading File] U.S. Government ATSDR Science Corner - 2.5MB PDF
• MINERAL CONTENT of WATER - water high in minerals, typically calcium or managanese, risk clogged pipes & water heaters
• MUNICIPAL WATER TEST PARAMETERS - how to check for pesticide contaminants in drinking water
  
  (also see WATER TEST MUNICIPAL)
• PESTICIDE CONTAMINATION in WATER - water test parameters - how to check for pesticide contaminants in drinking water - also see  
  
  PESTICIDES in WATER: TEST PARAMETERS
• SHOCK or CHLORINATE a WELL, HOW TO - Procedure for Shocking a Well to (temporarily or maybe longer) "Correct" Bacterial Contamination
• SWIMMING WATER TESTS - CONTENTS: options for testing swimming water for coliform level for swimming safety at lakes, rivers & ocean or salt water beaches. Marine water or seawater sanitation tests, testing standards, test procedures, & contaminants.
• TOTAL COLIFORM TESTING - also see BACTERIA TEST GUIDE
• TURBIDITY test for drinking water - can indicate whether the water supply is contaminated with groundwater or flood waters
• VA FHA STANDARD WATER TEST - water test parameters - how to check for pesticide contaminants in drinking water
• TDS WATER TEST - Total dissolved solids in water (also measures conductivity or a "conductivity test") identifies the mineral content of water. Water with high levels of salts or minerals may be a health hazard, and high mineral content or "hard water" risks problems with clogged plumbing equipment, pipes, water heaters. Also see WATER SOFTENERS & CONDITIONERS.
• TITLE 5 WATER TEST - water test parameters - how to check for pesticide contaminants in drinking water
• UV ULTRAVIOLET LIGHT WATER TREATMENT - Water treatment for bacteria using UV Lights - ultraviolet light sterilizers on water systems. How does an ultra violet light fixture correct bacterial contamination in well water? How do UV lights work? Details of proper UV light installation and maintenance for well water treatment. Water treatment methods for contamination, bacteria, lead, minerals, etc. Water treatment choices for odors, smells, sediment, cloudiness. Choices of types of water treatment equipment
  
  
  • UV light: This patent application for UV light sterilization www.patentstorm.us/patents/6565803.html Lists good references on water purification for Giardia et als
• VEGETABLE or PRODUCE DISINFECTION - what produce disinfection methods are suitable for home use? Warnings about the limitations of some DIY at home vegetable washes & produce disinfection. Surprise: distilled water performs as well as or even better than some store-bought produce disinfectant washes.
  
  How to use bleach to purify drinking water. Five years of testing & how to use SinBac™ or other vegetable disinfectants to prepare fruits, vegetables, or other foods for eating.
• VINEGAR as a disinfectant; Use of vinegar as a vegetable or fruit wash;
• WATER CONTAMINANT REMOVAL - removing aesthetic or functional contaminants in water such as Hardness, Odors, Sediment, Etc: choices of systems, recommendations
• WATER DISINFECTANT QUANTITY - how much bleach is needed to disinfect a well, water piping, water tanks

• WATER QUANTITY REQUIRED - For Home & Outdoor Living - how much water do people use, how much water do people need? This data is helpful for assessing well flow rate adequacy and for septic system or other wastewater disposal system design
• WATER TESTING ADVICE for HOME BUYERS - and also for home buyers home owners home inspectors
• WATER TEST RESULT INTERPRETATION - what the results mean and what to do about them
• WELL DISINFECTANT pH ADJUSTMENT - unless you get the pH right, disinfecting a well may be ineffective
• WATER TREATMENT EQUIPMENT CHOICES - home

Standards for Coliform in Drinking Water

Question: is our water safe to drink if coliform is detected?

2018/10/16 Pradeep said:

I have tested our drinking well water. In it the total Coliforms MPN/ 100 ml is 1600, Thermotolerant coliforms MP N/ 100 ml is 175, and Escherichia coli MP N/ 100 ml is less than 2.

Is the water good for drinking and how can we get the waterpurified?

Reply: no.

No Pradeep, by US standards and those used in some other countries,

The Maximum Acceptable Concentration of both Total Coliforms and E-Coli for Drinking Water is ** none detectable per 100 mL **

This means that for every 100 mL of drinking water tested, NO total coliforms and NO E.coli should be detected.

While total coliform is common in groundwater and is not necessarily harmful itself, when it is found in drinking water it should be understood to be an indicator that unsanitary water is entering the water supply.

When E-coli (Echeria coliform) is present in drinking water it is harmful, containing pathogens that can cause serious illness.

For details about bacteria testing in the water supply you may want to

read BACTERIA TEST GUIDE - tests the level of microbial ccontaminants in water.

Examples of Coliform Standards for Drinking Water

Canadian Standards for Coliform Levels in Drinking Water

The Canadian Drinking Water Quality Guideline for total coliforms is none detectable per 100 mL.

The Canadian Drinking Water Quality Guideline for Escherichia coli (E.coli) is none detectable per 100 mL.

Maximum Acceptable Concentration for Drinking Water = none detectable per 100 mL

• FACTS ON DRINKING WATER - Coliform Bacteria – Total Coliforms & E.Coli [PDF] - Canada, New Brunswick, retrieved 2018/10/16, original source: www.rpc.ca/english/pdf/water/Coliforme.pdf

Mexico Sanitation & Water Quality Standards

According to the Mexican constitution responsibility for water supply and sanitation services delivery rests with 2,517 municipalities since the decentralization of 1983. (Pablos 2002)

• Pablos, Nicolas Pineda: LA POLITICA URBANA DE AGUA POTABLE EN MEXICO: del centralismo y los subsidios a la municipalización, la autosuficiencia y la privatización. May 2002
  
  Este artículo presenta la evolución institucional y legal del servicio urbano de agua potable en México durante la segunda mitad del siglo X X.Además de ofrecer un breve esquema de análisis de la política pública, en la parte principal se proponen tres etapas esenciales por la que ha pasado esta política.
  
  Dichas etapas se basan en el tipo de arreglo institucional que caracterizó a la prestación del servicio de agua potable en cada periodo.
  
  La primera es la etapa centralista de las juntas federales de agua , prevaleciente de 1948 a 1983;
  
  después viene la etapa de la municipalización, iniciada en 1983 en que el servicio se asigna a los gobiernos locales y,
  
  en tercer lugar, está la promoción de organismos operado res autónomos y manejados como empresas, iniciada por la Comisión Nacional del Agua a partir de 1989 .
  
  Al final, se revisan las vicisitudes del impulso a la participación del sector pri vado en el servicio urbanode agua y el trastorno que éste tuvo ante la crisis económica de 1995.
• WATER QUALITY, SANITATION TECHNOLOGY FOR THE AMERICAS [PDF] (1996-2018) Mexican Official Standard NOM-001-ECOL-1996 - Cepis retrieved 2018/10/16, original source: http://cepis.org.pe/mexican-official-standard-001ecol1996/
  
  This Mexican Official Standard establishes the maximum permissible limits of pollutants in discharges of wastewater dumped into national waters and goods, in order to protect its quality and enable their uses, and is mandatory for those responsible for such discharges.
  
  This Mexican Official Standard does not apply to discharges of water from separate storm drainage.
• Norma Oficial Mexicana NOM-001-ECOL - 1996 [PDF]
  
  Esta Norma Oficial Mexicana establece los límites máximos permisibles de contaminantes en las descargas de aguas residuales vertidas a aguas y bienes nacionales, con el objeto de proteger su calidad y posibilitar sus usos, y es de observancia obligatoria para los responsables de dichas descargas.
  
  Esta Norma Oficial Mexicana no se aplica a las descargas de aguas provenientes de drenajes pluviales independientes.

UK United Kingdom Drinking Water Standards including for Coliform

• WHAT ARE THE DRINKING WATER STANDARDS [for the UK] ? [PDF] retrieved 2018/10/16, original source: http://dwi.defra.gov.uk/consumers/advice-leaflets/standards.pdf
  
  These standards include coliform and E-coli and require that both be at a level of zero at consumer taps: 0/100 ml. for Enterococci, Escherichia coli.
  

United States Standards for Coliform in Drinking Water

Excerpts:

For E. coli (EC), the Maximum Contaminant Level Goal (MCLG) is set at zero.

Total coliforms are a group of related bacteria that are (with few exceptions) not harmful to humans. A variety of bacteria, parasites, and viruses, known as pathogens, can potentially cause health problems if humans ingest them.

EPA considers total coliforms a useful indicator of other pathogens for drinking water.

Total coliforms are used to determine the adequacy of water treatment and the integrity of the distribution system.

• REVISED TOTAL COLIFORM RULE AND TOTAL COLIFORM RULE [PDF] retrieved 2018/10/16, original source: US EPA https://www.epa.gov/dwreginfo/revised-total-coliform-rule-and-total-coliform-rule
• REVISED TOTAL COLIFORM RULE: A QUICK REFERENCE GUIDE [PDF] US EPA - retrieved 2018/10/16, original source: nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100K9MP.txt
• TOTAL COLIFORM RULE: A QUICK REFERENCE GUIDE [PDF] US EPA, Total Coliform Rule (TCR) 54 FR 27544-27568, June 29, 1989, Vol. 54, No. 1241 - retrieved 2018/10/16, original source: nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=3000663W.txt
• DRINKING WATER REGULATIONS, U.S. [Website] The complete regulations regarding these contaminants available from the Code of Federal Regulations Website -(United States)
• DRINKING WATER CONTAMINANT WATER LIMITS [InspectApedia.com article] - what are the maximum allowed or limits on various contaminants found in drinking water. Health Effects of Chemical Contaminants in Drinking Water, US Environmental Protection Agency, others.

Watch out: people with weakened immune systems may be more vulnerable to pathogens or other contaminants in drinking water. Treatments that kill coliform bacteria are generally not effective against other pathogens that may be present. See:

• CRYPTOSPORIDIUM: GUIDANCE FOR PEOPLE WITH SEVERELY WEAKENED IMMUNE SYSTEMS, [PDF] (1995) A joint EPA and CDC guidance document for people who are immunocompromised, US EPA, retrieved 2018/10/16, original source: https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=200024LD.txt
  
  Excerpts:
  Cryptosporidium is a parasite commonly found in lakes and rivers, especially when the water is contaminated with sewage and animal wastes.
  
  Cryptosporidium is very resistant to disinfection, and even a well-operated water treatment system cannot ensure that drinking water will be completely free of this parasite.
  
  Current EPA drinking water standards were not explicitly designed to assure the removal or killing of Cryptosporidium.
  
  Many large water systems already [in 1995] voluntarily take actions for greater control of Cryptosporidium and other microbial contaminants.
  
  By 2001, the water systems serving the majority of the United States population (those relying on a surface water source, such as a river, and serving more than 10,000 people) must meet a new [in 1995] EPA standard that strengthens control over microbial contaminants, including Cryptosporidium. EPA continues to conduct research on microbial contaminants which will be used for determining priorities for the drinking water program, including setting future standards and reevaluating existing standards.
  
  Cryptosporidium has caused several large waterborne disease outbreaks of gastrointestinal illness, with symptoms that include diarrhea, nausea, and/or stomach cramps.
  
  People with severely weakened immune systems (that is, severely immunocompromised) are likely to have more severe and more persistent symptoms than healthy individuals. Moreover, Cryptosporidium has been a contributing cause of death in some immunocompromised people.
  
  Individuals who are severely immunocompromised may include those who are infected with HIV/AIDS, cancer and transplant patients taking immunosuppressive drugs, and people born with a weakened immune system.
  

WHO World Health Organization Drinking Water Guidelines & Coliform Standards

• Vol. 1 GUIDELINES FOR DRINKING-WATER QUALITY. VOL. 1, RECOMMENDATIONS, 3rd ed. Geneva: World Health Organization. Water, Sanitation and Health Team. (‎2004)‎ - retrieved 2018/10/16, original source: http://www.who.int/iris/handle/10665/42852
  
  Excerpts
  Significance in drinking-water Total coliforms should be absent immediately after disinfection, and the presence of these organisms indicates inadequate treatment.
  
  The presence of total coliforms in distribution systems and stored water supplies can reveal regrowth and possible biofilm formation or contamination through ingress of foreign material, including soil or plants.
  
  While E. coli is a useful indicator, it has limitations.
  
  Enteric viruses and protozoa are more resistant to disinfection; consequently, the absence of E. coli will not necessarily indicate freedom from these organisms.
  
  Under certain circumstances, it may be desirable to include more resistant microorganisms, such as bacteriophages and/or bacterial spores.
  
  Such circumstances could include the use of source water known to be contaminated with enteric viruses and parasites or high levels of viral and parasitic diseases in the community.
• Vol. 1 Addendum, RECOMMENDATIONS, MICROBIOLOGICAL AGENTS in DRINKING WATER PDF] discusses Aeromonas, Enteric hepatitis viruses, Legionella, Protozoan parasites ( Cryptosporidium, Giardia, Cyclospora) - retrieved 2018/10/16, original source: apps.who.int/iris/bitstream/handle/10665/42852/9241546387.pdf?sequence=1&isAllowed=y
• Vol. 2: HEALTH CRITERIA SUPPORTING INFORMATION [PDF] - retrieved 2018/10/16, original source:
• Vol. 3: DRINKING WATER QUALITY in SMALL COMMUNITY SUPPLIES, [PDF] 2nd ed. - retrieved 2018/10/16, original source:

What to Do About Coliform in Drinking Water

If coliform is the only contaminant in drinking water AND after establishing that you can't correct the problem by shocking the well and fixing surface water leaks into the well then you will want to install a water disinfection system.

Watch out: before installing any water treatment system for bacteria you should have more-extensive water testing done to find out if there are other non-bacterial contaminants that also need to be removed.

That's because the presence of coliform in drinking water often means that surface water is leaking into the water supply.

When surface runoff leaks into a drinking water supply, any contaminants present on the surface, including for example pesticides or agricultural chemicals, are likely to be in the water and also are likely to be at levels meriting removal.

...

Continue reading at WATER QUALITY TEST CHOICES & WATER TEST FEES - how to decide what to test for in your water supply, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• BACTERIA LEVELS in WATER, INTERPRETATION
• CHEATING ON WATER TESTS that warns about how people accidentally or on purpose can obtain incorrect water test results.
• CONTAMINANT CLASSES, in WATER
• CORROSIVITY or ACIDITY of WATER
• FAILED WATER TESTS - WHEN to RE-TEST
• MEASURE WATER HARDNESS
• WATER CONTAMINANT LEVELS & LIMITS
• WATER TEST PROCEDURAL ERRORS
• WATER TESTS for CONTAMINANTS - home
• WATER QUALITY TEST CHOICES & WATER TEST FEES - home - how to decide just which water tests to order.
• WATER TEST PROCEDURAL ERRORS
• WATER TEST RESULT INTERPRETATION - what the results mean and what to do about them
• WATER TESTING ADVICE for home buyers and building owners: water contaminants, water test procedures, well shock procedures, preventing drinking water contamination,
• WATER TREATMENT EQUIPMENT CHOICES - home- options for water disinfection, treatment, purification, or removal of other un-wanted substances
• WELL FLOW RATE

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WATER TESTS for CONTAMINANTS 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 TESTING

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