In the United States, more than 23 million households get their
drinking water from private wells. Unlike public drinking water systems, these wells are not regulated for safety by federal or state government. They can become polluted by many substances and cause kids to get sick.
If your family drinks water from a private well, it's important to
test the water regularly to make sure it's safe. It's also a good idea to ask about testing if your children drink well water at child care, school,
camps or when your family travels.
How often should your well water be tested?
The American Academy of Pediatrics (AAP) recommends that if your family drinks well water, the well should be tested once a year for coliform bacteria and nitrates.
You may need to test your well water more often if:
Someone in your household is pregnant or nursing
There is a new infant or a child under 1 year of age in the home
You've had unexplained illnesses in your household
Your neighbors find a dangerous contaminant in their well water
The smell or taste of your well water changes
There's a chemical spill near your well
There are new fracking operations, underground chemical storage tanks or other industrial operations in your area that could contaminate the ground water
You had a major repair or replacement in your well
flooding or another disaster that may have contaminated your well
Are children at higher risk from contaminated well water?
Kids are more likely to pick up an illness from contaminated water than adults. This means that just because adults can drink the water without any problems, that doesn't mean a child can.
Types of well water contaminants
The main types of contaminants that can pollute wells come from chemicals and microorganisms (bacteria, viruses, fungi and parasites). You can find a list of all the regulated drinking water contaminants
How do contaminants get into well water?
All water naturally contains chemical elements. The natural chemical composition of well water varies with region, underlying geology and type of aquifer. The problem is when the water becomes polluted with potentially toxic chemicals. This can happen from naturally occurring chemicals in the well, such as arsenic, manganese and radium. It can also be caused by runoff from nearby industry, farms or businesses.
Pollutant chemicals in well water may include nitrate and nitrite, heavy metals, organic chemicals including pesticides and per- and polyfluoroalkyl substances (PFAS), and radionuclides.
Microorganisms (bacteria, viruses, fungi and parasites) can also pollute groundwater that supplies wells and cause illness. The biggest source of these microorganisms is solid waste from animals and humans. In 2013-2014, the Centers for Disease Control and Prevention reported 42 U.S. waterborne disease outbreaks, causing 1,006 cases of illness, 124 hospitalizations and 13 deaths.
Other factors that can affect well water safety
- Climate change & disasters can affect drinking water, including private wells. Extreme weather events such as hurricanes, droughts and flooding can pollute groundwater with chemicals or microorganisms. Disasters such as wildfires, war and terrorist attacks can also result in wells becoming contaminated. For example, radioactive substances can be released due to an earthquake or a tsunami.
- Hydraulic fracturing, also known as fracking, is another potential threat to drinking water. Fracking is a process of extracting oil or gas from underground rock. The fluids used in fracking can affect groundwater.
Chemicals in well water
Too much of these chemicals in drinking water can cause side effects:
Rock formations specific to the southeastern U.S. "slate belt," Nevada, Alaska, and other areas of the western U.S.
Bladder, skin and lung cancer in humans
Miscarriage, stillbirth and low birth weight
Skin pigmentation, melanosis and keratosis
Gastrointestinal, pulmonary, cardiovascular, endocrine, immune and neurotoxicity
10 ug/L maximum
Preventive for dental cavities
Supplement if concentration is low
Too much can cause dental fluorosis
Optimum level = 0.7 mg/L
Maximum contaminant level = 4 mg/L
Learning and behavior problems
Hearing and speech challenges
Red blood cell, kidney and bone toxicity
EPA maximum contaminant level for lead is 15ppb; the AAP has recommended a lower maximum safe lead level of 1 ppb for school drinking fountains
Under 0.3 mg/L
Methyl tertiary butyl ether
Nitrate and nitrite
Maximum contaminant level = 10 mg/L for nitrate
Maximum contaminant level = 1 mg/L for nitrite
Only certain states have guidance; in Massachusetts, it's 2 ug/L maximum, in California, it's 6 ug/L maximum
Perfluoroalkyl and polyfluoroalkyl substances (PFAS)
Landfills, military or industrial sources
Consumer products such as nonstick cookware and stain repellents
May be linked to health problems such as cancer, low birth weight, reduced fertility, impaired immune response, thyroid abnormalities, increased cholesterol and uric acid
Depends on specific chemical
No enforced drinking water standard
Maximum contaminant level = 30 ug/L
Volatile organics and pesticides
Dry cleaning, gasoline, agriculture, etc.
Often unable to be identified
A word about nitrates
Studies show that a substantial number of private wells contain levels of nitrates that are too high. Nitrates are a natural part of plants and nitrate-containing fertilizers. They can seep into well water and can't pose any toxic risk to humans. In the body, they can be converted to nitrites, which are also potentially hazardous. Boiling doesn't remove them.
In infants, nitrates can lead to a dangerous condition called methemoglobinemia. This is a blood disorder that interferes with the circulation of oxygen in the blood.
Formula that is prepared with well water may put babies at risk of nitrate poisoning.
If your well water contains a level above 10 mg/L, it should not be used in infant formula or food. Instead, use purchased water, public water supplies or water from deeper wells with minimal nitrate levels.
Bacteria & other microorganisms in well water
To check for microorganisms, test your water for "total coliform bacteria." Most coliform bacteria don't cause disease. But if they're in your well water, this means that your water might be contaminated with microorganisms.
Examples of harmful microorganisms that may be found in well water include:
Escherichia coli (E coli), including O157:H7
Norovirus and sapovirus
Hepatitis A and E
Talk with your pediatrician
If you have concerns about contamination of your private well, stop using the water and consult your local or state health department and local individuals with known expertise in private well construction and remediation. Your pediatician can also be a resource. In addition, your regional Pediatric Environmental Health Specialty Unit (PEHSU) have staff who can also talk to you about your concerns.
You can find information about private drinking water well programs on the
U.S. Environmental Protection Agency (EPA) website.