What Are The Most Common Contaminants In Residential Wells?

? Do you know what could be hiding in the water coming from your well, and how to check specifically for manganese?

What Are The Most Common Contaminants In Residential Wells?

If you rely on a private well, you’re responsible for the safety of your drinking water. Groundwater typically starts out clean, but it can pick up a variety of contaminants from natural sources and human activities. This section covers the most common contaminants you’re likely to encounter in residential wells so you can recognize issues, prioritize testing, and choose appropriate treatment.

Why well contamination matters to you

Contaminants in well water can affect your health, your home (staining, clogging), and the taste and smell of your water. Some contaminants pose immediate health risks (for example, bacteria and nitrates for infants), while others are chronic concerns (like arsenic or radon). Regular testing helps you make smart decisions about treatment and safe water use.

How contaminants get into wells

Contaminants can enter wells through:

• Natural geologic sources (minerals and metals dissolved from bedrock and soils)
• Agricultural runoff (fertilizers, manure, pesticides)
• Septic systems and failing sewer lines (bacteria, nitrates, viruses)
• Industrial or urban contamination (volatile organic compounds, heavy metals)
• Surface water infiltration during heavy rains or flooding

Common biological contaminants

Biological contaminants are often the most urgent because they can cause immediate illness.

Coliform bacteria and E. coli

Coliform bacteria are used as an indicator of contamination by fecal material. If total coliforms are present, your well may be vulnerable to pathogens. E. coli specifically indicates fecal contamination and a higher risk of disease.

• Why you should test: Presence signals potential for harmful bacteria and viruses. Babies, elderly people, and people with weakened immune systems are particularly at risk.
• When to test: At least annually and whenever you notice changes after heavy rains, pump repairs, or flooding.

Viruses and protozoa

Viruses and protozoa (e.g., Giardia, Cryptosporidium) are less commonly tested by homeowners but can be present if sewage or animal waste contaminates the well.

• Testing approach: Typically requires lab testing and sometimes specialized sample collection (e.g., larger-volume samples for protozoa).

Common chemical contaminants

Chemical contaminants can be naturally occurring or introduced by human activity. Many have no taste or smell but carry health risks.

Nitrates and nitrites

Nitrates often come from fertilizer runoff, septic systems, or manure. They’re particularly dangerous for infants because they can cause methemoglobinemia (“blue baby” syndrome).

• What to watch for: High nitrate is common in agricultural areas. Test if you have young children, after fertilizer application seasons, or if you see changes in taste.
• Action level: Use lab results to guide decisions; if nitrate is elevated, avoid using untreated well water for infant formula.

Arsenic

Arsenic can occur naturally in groundwater depending on local geology. Long-term exposure increases the risk of cancer and skin issues.

• Why you should test: Arsenic has no taste or odor and long-term exposure is a chronic health risk.
• Common areas of concern: Certain regions have a higher natural occurrence; check local well maps or state resources.

Lead

Lead can come from old plumbing, fittings, or components in your home rather than directly from groundwater.

• Who’s at risk: Infants and children are most sensitive. If you have older plumbing, test for lead and consider replacing lead-bearing materials.

Iron and manganese

Iron and manganese are common naturally occurring metals. They affect aesthetics — creating stains and discoloration — and can foul plumbing and appliances. Manganese has additional health concerns at high levels, particularly for infants and children.

• Indicators: Rust-colored water (iron), black or dark brown staining and black particulates (manganese).
• Treatment: Different methods are needed for iron vs manganese depending on the chemical form (soluble vs particulate).

Sulfate

Sulfate can give water a bitter or medicinal taste and may cause diarrhea at high levels in people not used to it.

Fluoride

Fluoride occurs naturally in many groundwater sources. At low levels it can protect teeth; at higher levels it can cause fluorosis (cosmetic enamel changes) or other health concerns.

Volatile organic compounds (VOCs) and pesticides

VOCs (like solvents or gasoline components) and pesticides can get into wells through spills, leaking underground tanks, or runoff. These often require lab-based analytical methods to detect.

• When to test: If you live near agricultural operations, industrial sites, or fuel storage, test for VOCs and pesticides.

Radon

Radon is a radioactive gas that can enter water from surrounding rocks. It’s also a concern for indoor air if released from water during household use.

• Testing: Specialized radon-in-water tests are available; address both water and air if levels are elevated.

Health effects and indicators you can notice

You don’t always get symptoms from contaminated water, but some signs should prompt immediate testing:

• Cloudy, discolored, or foul-smelling water
• Black/brown staining on fixtures and laundry (manganese/iron)
• Metallic taste or sulfur (rotten egg) smell (hydrogen sulfide)
• Sudden changes after heavy rain or pump work
• Illness in people using the water (especially gastrointestinal)

How often you should test your well

At minimum:

• Test for bacteria and nitrates annually.
• Test for total dissolved solids (TDS), pH, and hardness every 1–3 years or if you notice changes.
• Test for arsenic, lead, and other regional concerns at least once to establish baseline; repeat if there’s reason to suspect change.
• Test after any well work or flooding, or when someone in the household is pregnant, nursing, or an infant.

How to get your well water tested

• Use a state-certified lab for accurate results.
• Local health departments typically maintain lists of certified labs and can help with sampling instructions.
• Collect samples using the lab’s containers and follow their instructions for preservation and shipping. Improper sampling is a common cause of inaccurate results.
• For common parameters (bacteria, nitrates, basic metals) you’ll get clear numeric results with interpretive guidance.

Table: Common well contaminants — sources, health effects, and common indicators

How do I test for manganese in my well water?

This is a common and practical question. Testing for manganese requires you to choose between quick field screening or reliable laboratory analysis depending on how precise you need the result to be and what actions you plan to take.

Why test specifically for manganese?

Manganese is common in groundwater in many areas. While small amounts are not usually acutely toxic, elevated manganese can:

• Stain laundry, plumbing fixtures, and appliances (brown/black stains)
• Produce black particulates that clog fixtures and filters
• Impart an unpleasant taste
• Pose potential neurological risks at higher concentrations, especially to infants and young children when ingested over time

If staining or black particulates are present, or if you have a newborn or young child, you should prioritize manganese testing.

Regulatory and guideline values to consider

• EPA Secondary Maximum Contaminant Level (SMCL) for manganese: 0.05 mg/L (50 µg/L). This is a non-enforceable guideline for taste, color, and staining.
• Health-based advisories: Different agencies have recommended limits based on health concerns. Some health advisories and international guidance reference higher values (hundreds of µg/L) as thresholds for potential health effects. Because guidelines have evolved, check the current EPA and your state health department guidance for the most up-to-date health-based recommendations.

If you’re testing because of health concerns (especially for infants), treat any detected elevated manganese as a serious issue and consult local health authorities.

Options to test for manganese

You have two main paths: field screening (home test kits or handheld meters) and certified laboratory testing. Use the table below to compare.

Table: Manganese testing methods — pros and cons

Step-by-step: Collect a sample for laboratory manganese testing

1. Contact a state-certified lab or your local health department to get the right sample bottle and instructions. Some labs provide pre-cleaned, acidified bottles for metal testing.
2. Choose the sampling tap: Use a cold-water tap that is not connected to a treatment system (or follow lab instructions if you want to test post-treatment).
3. Clean the faucet: Remove the aerator and disinfect the faucet with a mild bleach solution if lab instructions require it. Let the water run to flush the lines (typically 2–5 minutes).
4. Collect sample carefully: Fill the bottle to the indicated line without aerating the water. For metals, many labs require adding acid to preserve the sample — if the bottle is pre-acidified, do NOT rinse it out.
5. Cool and ship promptly: Put the sample on ice (4°C) and ship or deliver it to the lab as soon as possible. Some analytes require same-day delivery.
6. Complete paperwork: Fill out the chain-of-custody or sample information form and note any treatment devices between the well and the tap.

Tips for accurate manganese testing

• Use certified labs for accurate, low-level detection and for results you’ll act on (treatment, safety decisions).
• If you use home kits, treat results as indicative. Confirm elevated readings with a certified lab.
• Test both untreated well water and water after your treatment device if you want to assess treatment effectiveness.
• If you have iron also present, ask the lab to test for both, since they often occur together and affect treatment choices.

Interpreting manganese test results

• Below 0.05 mg/L (50 µg/L): This is below the EPA secondary standard for staining; aesthetic issues are unlikely. Still consider health context (infants).
• Between 0.05 mg/L and 0.3 mg/L: You may see staining issues and partial health concerns depending on guidance; consider treatment especially if you have children or are concerned about appliances.
• Above 0.3 mg/L (300 µg/L) and higher: Investigate treatment and consult local health guidance. For infants, consider alternative water sources for formula if manganese is elevated.

Always compare lab results to current federal, state, and local guidance and consult a professional if you’re uncertain.

What to do if your manganese test is elevated

If you get results showing elevated manganese, take the following steps:

1. Confirm with a certified lab if you initially used a field kit.
2. If you have an infant, pregnant person, or someone with health vulnerabilities, stop using untreated well water for formula and consult a healthcare provider.
3. Consider short-term alternatives for drinking and cooking (bottled water or other safe sources) until you have treatment in place.
4. Evaluate treatment options (see detailed section below).
5. Fix potential sources of contamination if introduced (e.g., well casing issues, nearby contamination sources) and consider well rehabilitation or relocation if necessary.

Table: Common treatment options for manganese — how they work and when to use them

Choosing the right treatment

• Determine the manganese concentration and speciation (dissolved vs particulate). Labs report “dissolved manganese” (filtered) — this matters for choosing treatment.
• Check water pH, iron content, presence of organics (which can interfere with oxidation), and total hardness. These affect the choice and operation of the treatment system.
• For low-to-moderate manganese (and no complex organics), a greensand or catalytic carbon filter often works well.
• For higher concentrations, you may need a multi-step system: oxidize first, then filter, possibly followed by polishing (carbon or RO).
• Consider whole-house vs point-of-use: staining and plumbing protection usually require whole-house systems; drinking concerns might be addressed at point-of-use (RO).

Maintenance considerations

• Filters and media need routine backwashing, regeneration, or replacement according to the manufacturer.
• Test treated water periodically to ensure system performance.
• For chemical systems, keep track of reagent supply (e.g., potassium permanganate) and safe handling procedures.
• Work with licensed contractors for system sizing, installation, and maintenance.

Cost considerations

• Lab testing: $25–$200+ depending on parameters and lab.
• Home test kits: $10–$50 (screening-level).
• Point-of-use RO systems: $200–$2,000 installed depending on model.
• Whole-house oxidation/filtration systems: $1,000–$7,000+ depending on complexity, capacity, and whether pretreatment is needed.
• Ongoing costs: media replacement, reagents, water usage for backwashing, and professional service.

When to get professional help

• If tests show manganese above health-based advisory levels or you have infants/pregnant individuals in the home.
• If you see persistent black particulates that clog fixtures or appliances.
• When you need a whole-house system sized and installed properly.
• If your well shows multiple contaminants or you suspect contamination sources nearby.

Preventing and reducing manganese issues at the source

• Keep potential contamination sources away from your well: septic systems, chemical storage, livestock yards, and fertilizer storage.
• Maintain a proper wellhead seal and a sanitary well cap.
• After floods or significant groundwater events, test your well for coliforms and other contaminants, including metals if staining appears.
• Consider well rehabilitation if the casing or screen is damaged or compromised.

Frequently asked practical questions

If I see black particles in my water, does that mean manganese?

Black particles are often manganese oxides, but they can also be organic material or other particulates. Testing will confirm manganese. Use a clean glass container to collect a sample and have a lab analyze it.

Can a water softener remove manganese?

Water softeners (ion exchange) can remove small amounts of dissolved manganese, especially if it’s in the Mn2+ form and at low concentrations. They’re not reliable if manganese is high or particulate; manganese can foul softener resin. Softening alone often isn’t the best long-term solution when manganese is a major issue.

Are manganese test strips reliable?

Test strips give a quick indication and are good for screening. They’re less precise and can be influenced by water color, iron, and user interpretation. Confirm positive or borderline results with a certified lab.

If my manganese is only slightly elevated, do I need treatment?

If manganese is slightly above aesthetic levels but below health advisory levels, treatment may be optional if staining or taste isn’t a concern. Still consider treatment if you have infants, young children, or vulnerable household members.

Final checklist: testing and follow-up

• Test your well annually for coliforms and nitrates.
• Test for manganese, arsenic, lead, and regional priorities at least once or more often if you suspect a problem.
• Use state-certified labs for confirmatory tests and before making major treatment investments.
• If you get elevated manganese results:
  • Confirm with a certified lab,
  • If infants are present, use alternative water for formula,
  • Consult public health or a water treatment professional,
  • Choose a treatment system based on concentration, water chemistry, and household needs,
  • Maintain the system and retest periodically to ensure ongoing protection.

Closing practical advice

You’re in control of your well water quality. Regular testing, prompt action on unusual signs (staining, black particles, taste changes), and correct selection and maintenance of treatment will keep your water safe and your plumbing protected. When in doubt, get a certified lab test and consult local health or water-treatment professionals to create a plan appropriate for your family and your well.

If you want, tell me your test results (concentrations or symptoms) and your household needs (infants, appliances, whole-house vs point-of-use), and I can help you interpret the results and outline specific treatment options.