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Well Water Testing

Coastal Bioanalysts is accredited by the Commonwealth of Virginia for the analysis of drinking water for Escherichia coli (E. coli) and coliform bacteria; the absence of these  contaminants constitutes the minimal potability requirements for private wells.  For other regulated contaminants, such as nitrate and lead, we can have client samples analyzed by partner labs that are accredited for those contaminants.  Nuisance contaminants, which may be important in evaluating and treating water for taste, staining, etc., can be measured in house as non-accredited parameters.

Please Note:  Many lenders have different analytical requirements for well water testing for property transfers.  The requirements do not necessarily depend on the type of the loan (e.g. FHA, VA) but are lender specific.   If in doubt, please check with your lender or real estate agent; please do not call the lab regarding specific requirements as we will not be able to answer your questions.  Also, do not wait until the last minute before closing to have your water analyzed.  Data are typically valid for at least 30 days and some analyses require several days to obtain results.


Bacteria Testing 


Many types of bacteria and viruses that can make you sick may occur in well water.  However, it would be extremely expensive and impractical to test for all of the different species and strains of organisms.  Instead, water is tested for indicator organisms. These indicator organisms are typically harmless; however, their presence indicates the potential for the presence of disease-causing organisms (pathogens).


Coliform bacteria are a type of bacteria found in the digestive tract of warm blooded animals, on soils and plants, and in surface waters.   The presence of these bacteria can be caused by many types of contamination including intrusion of rain or other surface waters due to cracked well casings, contaminated ground water, contamination from recent plumbing work, poor sampling technique, etc.


E. coli are a specific type of coliform bacteria that are found in the feces of warm blooded animals. Their presence is of greatest concern because contamination of water by fecal matter may cause diseases such as diarrhea, dysentery, and hepatitis. 

Well water bacteria should be tested when:

  • problems occur in or around the well (flooding, waste disposal, land disturbance),

  • there are known problems with wells in your area,

  • there is a change in water color, taste or odor,

  • you replace the well or parts of the system,

  • ownership of the property changes. Testing is typically required of lenders when buying a house.

Sampling for bacteria can be performed by the homeowner but care must be taken to avoid accidental contamination of the sample.  Alternatively, there are a number of companies (plumbers, well and water treatment companies) that will collect the samples for you, but the analyses must be performed by a state accredited laboratory.  Coastal Bioanalysts does not provide sample collection services. Detailed sampling instructions are provided in the following link: Sampling Instructions


What to do if bacteria are present in your well?  There is no EPA acceptable level of bacterial contamination (in other words, results should indicate none present).   The first step is to disinfect the well with chlorine (household bleach or swimming pool granular product).  This will eliminate contamination caused by an intermittent/transient source such as during construction and repair, or due to flooding.  After disinfection it is imperative to retest in order to confirm the well is no longer contaminated.  It is a good idea to wait a little while before retesting so that any slow or low level of contamination is detected.  


Guidance for well disinfection can be found at the Centers for Disease Control website below.  If in doubt, a plumber, well driller or water treatment company can disinfect your well for you.  Note: Coastal Bioanalysts does not perform these services and cannot offer advise on how to disinfect your specific water system.


Nitrite/Nitrate Testing (Subcontracted) 


Runoff from fertilizer use, leaching from septic tanks or sewage, and erosion of natural deposits can result in the presence of nitrate and nitrite in well water.   Microorganisms present in the soil can in turn convert nitrate to nitrite. Additionally, the stomachs of infants have relatively low acidity compared to adults, which allows the growth of certain microorganisms that convert nitrate to nitrite.


Nitrite is of particular concern because it causes the conversion of hemoglobin to methemoglobin, which reduces the oxygen carrying capacity of blood (methemoglobinemia).  Infants below the age of six months who drink water containing excessive nitrate or nitrite could become seriously ill and, if untreated, may die.
Symptoms include shortness of breath and blue-baby syndrome

Well water nitrate/nitrite should be tested when: 

  • a new baby is brought into the house,

  • a new well is installed,

  • a change in well water quality occurs,

  • buying a new property

Sampling should typically be performed between April and July when values tend to be highest.

Sampling for nitrate and nitrite can be performed by the homeowner.  Detailed sampling instructions are provided in the following link: Sampling Instructions

What to do if nitrites/nitrates are detected in your well water? EPA maximum contaminant levels (MCL) for nitrate are 45 mg/l (ppm) as nitrate, or 10 mg/l as nitrogen.  MCLs for nitrite are 3.3 mg/l (ppm) as nitrate, or 1 mg/l as nitrogen.  If values exceed these levels then the water must either be treated, or a new well is installed.  

Lead Testing (Subcontracted) 

Corrosion of household plumbing systems and erosion of natural deposits can result in the presence of lead in well water.  Lead levels will tend to be higher in household hot water systems than cold water. Because corrosion can be a source, water acidity can be a factor in the corrosion of plumbing systems. EPA recommends a pH between 6.5 and 8.5 Standard Units (SU) to avoid metals leaching (pH < 6.5 SU) and bad taste/mineral deposits (pH > 8.5).


Lead is of concern because in infants and children it can cause delays in physical or mental development;
children could show slight deficits in attention span and learning.  In adults it is associated with kidney problems and high blood pressure.

Well water lead should be tested when:

  • a new baby is brought into the house,

  • a new well is installed,

  • a change in well water quality occurs,

  • buying a new property

Sampling is best performed on a system where the water has not been used that day to in order to assess lead that may leach from the plumbing.  

Sampling for lead can be performed by the homeowner.  Detailed sampling instructions are provided in the following link: Sampling Instructions

What to do if lead is detected in your well water? EPA has a goal of "zero" lead in public water supplies and an action level of 0.015 mg/l.  Keep in mind that laboratories cannot analyze to a zero level; a report of "less than detection limit" is the analytical equivalent of zero.  If unacceptable lead levels occur the water will need to be treated.  Replacement of plumbing systems may also help, especially if the existing system is older with soldered joints.


Nuisance Contaminants 

Hardness, pH, alkalinity, iron and total dissolved solids (conductivity) are other parameters for which there are no EPA drinking water standards but which can have an impact on water quality in terms of taste and staining of appliances and clothes due to mineral deposits.  Hardness is a measure of certain divalent cationic metals (primarily calcium and magnesium).  Depending on the pH and alkalinity, given levels of hardness or iron may result in the formation of deposits on household plumbing and appliance surfaces and may cause staining of clothing washed in the water. 


Water can be treated by "softening" or by reverse osmosis to remove unwanted minerals.  The choice of treatment options depends on the levels and types of dissolved materials present.  While treatment companies will typically analyze water for these parameters, many homeowners desire additional analyses by an independent lab.


Detailed sampling instructions for these nuisance contaminants are provided in the following link: Sampling Instructions

Additional information on well water quality:

NELAP Accredited Laboratory
Certifications and Accreditation

We are certified by the State of Virginia for the testing of drinking water for coliform bactia and E. coli.  Click here for a copy of our current  certificate.

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