What Health Risks Are Linked To Unsafe Well Water?

?Are you confident that your well water is safe for you and your family after heavy rains or routine use?

What this article covers

This article explains the health risks linked to unsafe well water and answers whether stormwater infiltration can affect well water safety. You’ll learn about the common contaminants, how they reach your well, the health effects they can cause, how to test and interpret results, and practical steps you can take to protect and treat your well. The goal is to give you clear, actionable information so you can keep your water safe.

Why well water safety matters

Your private well is your responsibility, and unlike public water systems, private wells generally aren’t regulated by federal agencies. That means you need to test and maintain your well to protect your health. Contaminated well water can cause immediate illnesses and long-term health problems, so understanding risks and prevention steps matters.

How water becomes unsafe

Water becomes unsafe when contaminants enter the well or the area around it. Contaminants can come from natural sources (rock and soil), human activities (septic systems, agriculture, industry), or storm events that move pollutants into groundwater. Knowing how contamination happens helps you reduce risk and choose the right tests and treatments.

Pathways: How contaminants reach your well

Contaminants reach wells through several pathways. They can infiltrate from surface runoff, migrate through soil and rock, or enter the well through cracks, unsealed openings, or a poorly constructed wellhead. Stormwater infiltration is a major pathway after heavy rains and floods.

Can stormwater infiltration affect well water safety?

Short answer: yes. Stormwater infiltration can carry surface contaminants into groundwater and wells, especially if your wellhead is not properly sealed or protected. Heavy rainfall and flooding can overwhelm septic systems, wash pesticides and fertilizers from lawns and fields, and mobilize pollutants from roads and industrial sites into the groundwater that feeds your well.

How stormwater increases contamination risk

Stormwater can:

• Wash bacteria and viruses from animal waste into groundwater.
• Move fertilizers and pesticides into aquifers, increasing nitrate and pesticide concentrations.
• Carry petroleum and other hydrocarbons from roadways and storage areas.
• Cause septic systems to overflow, releasing pathogens and nutrients.
• Recharge shallow aquifers rapidly, reducing natural filtration and increasing the chance that contaminants reach the well.

Types of well contaminants and how they affect health

Contaminants fall into broad categories: biological (microorganisms), chemical (inorganic and organic), radiological, and physical (sediment). Each type has different health implications and treatment requirements.

Biological contaminants

Biological contaminants include bacteria, viruses, and protozoa. These are often introduced by surface runoff, septic failures, animal waste, or human waste.

• Common organisms: total coliforms, E. coli, Enterococci, Giardia, Cryptosporidium, norovirus, hepatitis A.
• How you’re exposed: primarily by drinking water, but also by inhalation of aerosols (e.g., showering) or by accidental ingestion during bathing.
• Health effects: gastrointestinal illness (diarrhea, vomiting, stomach cramps), fever, and for vulnerable people (infants, elderly, immunocompromised), severe or life-threatening infections.

Chemical contaminants — inorganic

Inorganic chemicals often come from natural geology or agricultural and industrial activity.

• Nitrate/nitrite: Often from fertilizers, animal manure, septic systems. High nitrate levels can cause “blue baby syndrome” (methemoglobinemia) in infants and increase risk for pregnancy complications. The EPA’s MCL for nitrate as N is 10 mg/L.
• Arsenic: May occur naturally in groundwater or from industrial pollution. Long-term exposure increases risk of skin lesions, cardiovascular disease, and certain cancers (skin, bladder, lung).
• Lead: Usually not from groundwater itself, but from plumbing, solder, and fixtures. Chronic exposure affects neurological development in children and can cause cardiovascular and kidney problems in adults.
• Copper: Often from plumbing corrosion. High levels can cause gastrointestinal distress and, with chronic exposure, liver or kidney damage.
• Fluoride, manganese, iron, radon, uranium: These have various health impacts from dental and skeletal effects (fluoride), neurological effects (manganese), to cancer and kidney damage (uranium, radon).

Chemical contaminants — organic

Organic chemicals include pesticides, herbicides, petroleum hydrocarbons, industrial solvents, and increasingly, PFAS (per- and polyfluoroalkyl substances).

• Pesticides and herbicides: Linked to various health outcomes including endocrine disruption, reproductive issues, and cancers.
• Volatile Organic Compounds (VOCs) such as benzene, toluene, trichloroethylene (TCE): Can cause headaches, liver and kidney damage, and increased cancer risk with long-term exposure.
• Petroleum hydrocarbons: Often from fuel leaks or spills. Can cause acute symptoms (nausea, headaches) and chronic effects if exposure persists.
• PFAS: Known as “forever chemicals,” they accumulate in the body and are associated with immune, developmental, and possible cancer risks.

Radiological contaminants

Radioactive elements like radon, uranium, and radium may occur in groundwater depending on local geology. Radon gas in water can release into indoor air during household use and increase lung cancer risk. Uranium affects kidneys and has radioactive and chemical toxicity.

Physical contaminants

Sediment and turbidity don’t usually pose health threats directly, but they can protect microorganisms from disinfection and indicate that infiltration or well casing issues exist.

Acute vs. chronic health risks

Understanding the difference helps you prioritize testing and treatment.

• Acute risks: Caused by pathogens or high concentrations of certain chemicals (e.g., nitrate in infants). Symptoms appear quickly — hours to days — and often include gastrointestinal illness.
• Chronic risks: Result from long-term exposure to contaminants like arsenic, lead, PFAS, or radium. These can lead to cancer, developmental problems, reproductive harm, neurological decline, and organ damage over years.

Who is most vulnerable?

Certain populations are more susceptible to waterborne risks:

• Infants and young children (higher intake per body weight, developing systems).
• Pregnant people (fetal development concerns with nitrate, lead, arsenic).
• Older adults (weaker immune response).
• Immunocompromised individuals (cancer patients, people with HIV/AIDS, organ transplant recipients). If someone in your household falls into these groups, you should be especially proactive about testing and treatment.

Symptoms that may indicate contaminated well water

If you suspect contamination, watch for:

• Gastrointestinal issues: diarrhea, nausea, vomiting, abdominal cramps.
• Unusual tastes, odors, or discoloration (e.g., metallic taste, rotten egg smell indicating hydrogen sulfide or bacteria).
• Cloudy or muddy water after rains (indicates turbidity and possible infiltration).
• Staining on fixtures (iron, manganese).
• Health symptoms tied to chronic exposures (persistent headaches, fatigue, developmental delays in children, or skin changes). These signs aren’t diagnostic, so testing is necessary for confirmation.

How often should you test your well?

Regular testing is essential because conditions can change over time.

Recommended testing frequency

• Bacteria (total coliforms and E. coli): At least once a year and immediately after heavy rain, flooding, or septic system repairs.
• Nitrate: At least once a year, more often if you have a young infant or agricultural activity nearby.
• Lead, copper: Test if you have old plumbing or if water chemistry changes (acidic or soft water can leach metals).
• Pesticides/VOCs/other site-specific chemicals: Test when you suspect contamination (near farms, garages, industrial sites) or after evidence of spills.
• PFAS and other emerging contaminants: Test if you’re in a region with known industrial sources or firefighting foam use; otherwise test based on local guidance.

Table: Typical testing schedule and priority

How to test your well

Use certified laboratories and follow proper sampling procedures. Local health departments often provide sampling kits and instructions.

Steps for proper sampling

• Use sterile bottles provided by labs for bacteria testing; don’t touch the inside or cap.
• Run the water cold and collect from a tap that’s not connected to filters.
• Disinfect the faucet if required and let water run to clear stagnant water.
• Follow lab instructions on how to store and transport samples; many tests must reach the lab within 24 hours.
• Maintain records of results and dates.

Choosing a lab

Use state-certified or accredited labs. Your local health department can recommend labs and interpret results for local standards.

Interpreting test results

Understanding limits helps you know what to do.

• Private wells aren’t regulated by the EPA, but federal standards (Maximum Contaminant Levels, MCLs) for public water systems are useful benchmarks.
• For bacteria: any E. coli is a serious sign — treat water as unsafe and retest after corrective action.
• Nitrate: EPA MCL as nitrogen = 10 mg/L; infants are at high risk above that level.
• Arsenic: EPA MCL = 10 µg/L. Consider treatment at or above that level.
• Lead: No safe level; use 15 µg/L (action level) as an indicator for public systems, but for households, aim for as close to zero as possible.
• PFAS: Many states now have advisory or regulatory values; these are evolving. Consult local guidance.

Treatment options: how to make your water safe

Treatment depends on the contaminant. Some systems address multiple contaminants; others are specific.

Table: Treatment technologies and what they remove

Point-of-use vs whole-house systems

• Point-of-use (POU) systems like under-sink RO or carbon filters protect drinking and cooking water. They’re cost-effective when contaminants are limited to ingestion concerns.
• Whole-house (point-of-entry) systems treat all water entering your home, protecting showers, baths, and appliances. These are preferable when contaminants pose inhalation or dermal exposure risks or when water affects plumbing and appliances.

When to disinfect or shock chlorinate

After flooding or bacterial contamination, shock chlorination can disinfect your well. This treats the well temporarily but doesn’t fix structural vulnerabilities that allow recontamination. Follow guidelines or hire a professional.

Protecting your well from contamination

Prevention is usually less costly and more reliable than treatment.

Well construction and maintenance

• Ensure your well has a sanitary well cap and that the casing extends above grade with sealed access points.
• The well should be grouted and properly cased to prevent surface water infiltration.
• Keep the area around the well sloped away from the casing to direct runoff away.
• Have a licensed professional inspect your well regularly (every few years) and after events like floods or earthquakes.

Manage nearby hazards

• Maintain septic systems; pump periodically (typically every 3–5 years) and repair leaks.
• Store fuels, pesticides, and fertilizers away from the well and on impermeable surfaces.
• Use proper setbacks: keep livestock, manure piles, chemical storage, and gasoline tanks at recommended distances from wells (local codes vary).
• Avoid drainage ditches or ponds next to wells.

Landscaping and stormwater control

• Grade landscaping so surface water flows away from your well.
• Direct gutters and downspouts away from the well using extensions.
• Consider vegetative buffers or swales to slow and filter runoff.
• Ensure driveways and paved areas have controlled drainage that doesn’t flow toward the well.

What to do after a storm or flood

If your area experienced heavy rain, flooding, or septic overflow, act quickly.

Table: Immediate actions after a flood or heavy rain

Steps for shock chlorination (overview)

Shock chlorination can be done by homeowners but must be done carefully:

1. Determine the volume of water in the well. This requires knowing the well depth and casing diameter.
2. Calculate the amount of unscented household bleach needed to reach a target concentration (often 50–200 ppm depending on guidance).
3. Add bleach to the well, circulate through the plumbing, and let sit for the recommended contact time (typically 6–24 hours).
4. Flush the chlorinated water from the system until chlorine smell is gone.
5. Test for bacteria after disinfection to ensure effectiveness. Consider hiring a licensed well contractor if you’re unsure.

Long-term management and planning

Treating contamination is not a one-time fix. Long-term planning includes:

• Routine testing and record-keeping.
• Scheduled maintenance and inspections.
• Upgrading well construction or replacing old wells when necessary.
• Working with neighbors, farmers, and local agencies to reduce regional risks (e.g., pesticide runoff, industrial discharges).

Costs and what to expect

Costs vary widely depending on tests and systems:

• Basic bacteria/nitrate test: typically $20–$100 depending on lab and region.
• Comprehensive testing for a suite of parameters (metals, VOCs, pesticides): $200–$500 or more.
• Treatment systems:
  • Water softener/ion exchange: $800–$3,000 installed.
  • Reverse osmosis under-sink: $200–$1,000 (plus maintenance).
  • Whole-house filtration or GAC systems: $1,500–$6,000.
  • Well repair or replacement: varies widely; new wells can cost several thousand to tens of thousands of dollars depending on depth and geology. Budget for ongoing maintenance: filter changes, media replacement, and periodic service.

Emerging concerns: PFAS and new contaminants

PFAS are persistent and mobile in groundwater and resist typical treatment. States are developing standards, and specialized media (GAC, ion exchange, GFA) and RO can reduce concentrations. If you live near industrial sites, airports, or areas where firefighting foams were used, test for PFAS.

When to get professional help

• You detect E. coli or persistent bacterial contamination.
• After a flood or the well was submerged.
• If tests show high levels of nitrates, arsenic, VOCs, or PFAS.
• If you have ongoing taste or odor problems, or discoloration.
• If your well casing appears damaged or the water level has changed suddenly. Licensed well contractors, certified water treatment specialists, and local health departments can help diagnose and correct problems.

Working with local health departments and utilities

Your local or state health department can:

• Provide sampling guidance and sometimes free or low-cost testing kits.
• Recommend certified labs and approved treatment methods.
• Offer information on known local groundwater issues and advisories. If there is a suspected regional contamination source, public agencies can coordinate broader testing and mitigation.

Sample scenario: heavy storm and what you should do

If heavy rains caused runoff from a nearby farm and your water becomes cloudy and has a sulfur-like odor:

1. Stop using water for drinking and cooking; use bottled water or boil water for at least 1 minute.
2. Inspect the wellhead for visible damage or debris.
3. Call your local health department for guidance and collect samples for bacteria and nitrates immediately.
4. Do not rely solely on filters until you know what the contaminant is; some systems won’t remove certain pesticides or nitrates.
5. If bacteria are confirmed, perform shock chlorination or hire a professional to disinfect and then retest.

Table: Common contaminants, sources, and health issues

Practical checklist to protect your well

• Test your water annually for bacteria and nitrates; test other parameters based on local risk.
• Inspect the wellhead and cap annually and after storms.
• Keep hazardous materials away from the well site.
• Pump and inspect your septic system regularly.
• Direct stormwater away from the well using proper grading and gutters.
• Install appropriate treatment systems based on confirmed contaminants.
• Keep records of tests, maintenance, and repairs.
• Contact professionals or health officials when in doubt.

Final recommendations

You’re the first line of defense for your well water. Regular testing, sound maintenance, and smart stormwater and septic management greatly reduce the risk of contamination. If heavy rains or flooding occur, treat water as suspect until testing confirms it’s safe, and act fast if tests show bacterial contamination or dangerous chemical levels. Use certified labs, follow recommended treatment guidelines, and consult professionals for complex problems or persistent contamination.

If you want, tell me where you live (state or region) and details about your well (depth, age, nearby potential contamination sources), and I can suggest specific tests to prioritize and practical next steps tailored to your situation.