Well Water Contaminants & Their Health Impacts
A Guide for Private Well Owners
Drinking water can expose people to harmful pollutants and pathogens. While public water systems treat and monitor water to protect consumers, private well owners are responsible for their own water safety. Understanding potential contaminants and their health effects is the first step to protecting your family and the environment.
Where Contaminants Come From
Private wells can be contaminated by natural sources and human activities. Below are the most common contaminants, their sources, and health risks.
1. Microorganisms
What they are: Bacteria, viruses, and parasites found in soil, sewage, and animal waste.
How they get in: Rainfall or snowmelt runoff, leaking underground storage tanks, and septic system leakage.
Health impacts: Gastrointestinal illnesses and infections.
2. Nitrate & Nitrite
What they are: Found in chemical fertilizers, sewage, and animal waste.
How they get in: Groundwater movement, surface seepage, and runoff.
Health impacts:
- Converts to nitrite in the body
- Most dangerous for infants under 6 months
- Causes methemoglobinemia (“blue baby syndrome”) – reduces blood’s oxygen-carrying ability
- Symptoms: shortness of breath, bluish skin
- Can be fatal if untreated
3. Heavy Metals
What they are: Arsenic, lead, cadmium, chromium, copper, selenium, antimony, and more.
Sources: Plumbing, mining, petroleum refineries, municipal waste, cement plants, natural mineral deposits.
How they get in: Groundwater movement and surface runoff.
Health impacts: Acute/chronic toxicity, liver/kidney/intestinal damage, anemia, cancer
4. Organic Chemicals
What they are: Found in household products, agriculture, and industry (pesticides, paints, solvents, pharmaceuticals, petroleum, disinfectants, inks, dyes).
How they get in: Waste disposal, spills, runoff.
Health impacts: Damage to kidneys, liver, circulatory system, nervous system, and reproductive system
5. Radionuclides
What they are: Radioactive elements like uranium and radium.
Sources: Uranium/mining/milling, coal mining, nuclear power, naturally occurring in some groundwater.
How they get in: Groundwater flow, wastewater seepage, flooding.
Health impacts: Kidney toxicity, increased cancer risk
6. Fluoride
What it is: Naturally present in many aquifers.
Benefits: Prevents tooth decay in moderate amounts.
Health impacts from excess:
- Skeletal fluorosis: bone/joint pain and tenderness
- Dental fluorosis: tooth discoloration and pitting (during tooth development)
Quick Reference: Contaminant Risk Checklist
Use this table to identify activities near your well that may pose contamination risks.
| Activity Type | Potential Contaminant Sources |
|---|---|
| Agriculture | Fertilizer use/storage, animal feedlots, manure spreading/burial/lagoons, pesticide application (including aerial), field irrigation, waste disposal wells |
| Commercial | Airports, boatyards, rail yards, junkyards, recycling/waste stations, auto shops, carwashes, laundromats, dry cleaners, paint shops, gas stations, construction sites, golf courses, floor drains, labs, medical facilities, funeral homes, cemeteries |
| Industry | Oil/gas production & storage, pipelines, refineries, chemical manufacturing/storage, mining, electroplating, foundries, metal fabrication, machine shops, waste disposal wells, paper/textile mills |
| Residential | Fuel oil tanks, household chemicals, pool chemicals, septic tanks/leach fields, sewer lines, floor drains, lawn fertilizer storage/use |
| Other | Road de-icing, landfills, sewer/storm water pipes, abandoned or active disposal wells, illegal dumping |
For more on groundwater contamination, see the U.S. Geological Survey’s “Ground Water and the Rural Owner”.
Protect Your Well Water
- Test regularly for contaminants (at least annually)
- Maintain your well properly (secure cap, proper grading, regular inspections)
- Keep hazardous materials away from your wellhead
- Monitor nearby activities that could affect water quality
- Follow local regulations for waste disposal and chemical use
Your well water is your responsibility — but with awareness and action, you can keep it safe for your family and the environment.
Original Source:
U.S. Environmental Protection Agency: Potential Well Water Contaminants and Their Impacts