What to Test for in Well Water (Complete Contaminant Checklist)
Water Testing Guide
What to Test for in Well Water (Complete Contaminant Checklist)
A private well has no utility checking it for you. This is the complete, organized checklist of what to test your well water for, sorted into what every well needs, what to add if you have symptoms, and what to add based on where you live, with the EPA limit and the fix for each one.
TL;DR
Every private well should be tested at least once a year for total coliform bacteria and E. coli, nitrate, pH, hardness, iron, manganese, and total dissolved solids (TDS). That is the baseline the CDC and EPA recommend. Beyond that, add tests based on your symptoms (sulfur smell, staining, cloudy water) and your geography (arsenic, lead, radon, uranium, fluoride, PFAS, pesticides). You do not test these one at a time. A single comprehensive panel like the Well Water Test Kit ($199, 53 contaminants) covers all the baseline items plus most risk-based ones in one sample, and gives you the full chemistry needed to size any treatment system.
- Always test (every well, every year): coliform/E. coli, nitrate, pH, hardness, iron, manganese, TDS. See the how to test your well water guide.
- Test if you have symptoms: hydrogen sulfide (rotten egg smell), tannins (yellow water), sediment, copper (blue-green stains), chloride/sodium (salty taste).
- Test by geography/risk: arsenic, lead, radon, uranium, fluoride, PFAS, VOCs, and pesticides in agricultural areas.
- Once you have results, learn to read them with our test results guide, then send them to Aidan at 800-460-5810. No obligation.
Aidan Walsh, Mid Atlantic Water: "When someone calls me about their well, the first question I ask is, 'What does your test say?' If they do not have a test, that is where we start, because you cannot fix water you have not measured. The mistake I see most is people testing for the one thing they are worried about and missing the four things they did not know to look for. Test everything once, properly, and then we know exactly what your water needs. Guessing is how people buy the wrong equipment."
What This Guide Covers
The 3-Tier Testing Framework
If you are on a private well, no government agency and no water utility checks your water for you. Under the EPA's private well program, the responsibility for testing and treatment falls entirely on the homeowner. That sounds overwhelming until you realize the list of what to test for is short, predictable, and easy to organize into three priority tiers. (On city or municipal water instead? This well list does not apply. Start with your water quality report and our how to test your tap water guide.)
The trick is not to test for everything blindly. It is to test for the right things in the right order: the baseline panel every well needs, the symptom-driven items you add when something looks, smells, or tastes off, and the risk-based items that depend on your local geology and land use. Here is the framework in one view.
Always Test, Every Well, Every Year
Coliform bacteria and E. coli, nitrate, pH, hardness, iron, manganese, and TDS. These are the CDC and EPA baseline. Test them on every well at least annually, no exceptions.
Test If You Have Symptoms
Hydrogen sulfide (rotten egg smell), tannins (yellow or tea-colored water), sediment and turbidity (cloudy), copper (blue-green stains), chloride and sodium (salty taste). Add these when your water gives you a clue.
Test Based on Where You Live
Arsenic, lead, radon, uranium, fluoride, PFAS, VOCs, gross alpha, and pesticides/herbicides. These are invisible and depend on local bedrock, agriculture, and your plumbing. Many belong on a first-ever test for every well.
The One Idea That Saves You Money
You do not test these contaminants one at a time. A single comprehensive lab panel measures every Tier 1 item and most Tier 3 items from one water sample. That is cheaper than ordering five separate tests and, more importantly, it gives you the full water chemistry needed to size treatment correctly. More on that below.
Tier 1: Always Test (Every Well, Every Year)
This is the baseline. The CDC's guidelines for testing well water recommend testing at least once a year for total coliform bacteria, nitrate, total dissolved solids, and pH. We add hardness, iron, and manganese because they are nearly universal on private wells and they drive most of the equipment decisions homeowners actually face. Every contaminant below should be on your first test and your annual retest.
| Parameter | Why It Matters | EPA Limit | What a High Result Means & How to Fix It |
|---|---|---|---|
| Total Coliform & E. coli | Health. Indicator bacteria showing a path for surface contamination to reach your well. E. coli signals fecal contamination. | MCL: zero (any presence is a violation) | Disinfect and protect the well, then install continuous treatment. A UV disinfection system kills bacteria with no chemicals. See how to remove coliform bacteria. |
| Nitrate | Health. Linked to "blue baby syndrome" in infants under 6 months. Often signals fertilizer, septic, or animal-waste influence. | MCL: 10 mg/L (as nitrogen) | Confirm the source, then treat. Reverse osmosis at the tap or nitrate-selective ion exchange removes it. See the nitrates in well water guide. |
| pH | Cosmetic and infrastructure. Low pH (acidic) corrodes pipes and leaches copper and lead. High pH causes scaling. | SMCL: 6.5 to 8.5 (secondary) | Below 6.5, an acid neutralizer raises pH and stops corrosion. See how to test for low pH. |
| Hardness | Cosmetic and infrastructure. Calcium and magnesium cause scale, spotty dishes, dry skin, and reduced appliance life. | No EPA standard. >7 gpg is "hard" | A water softener exchanges hardness minerals for sodium. See how to test for hardness. |
| Iron | Cosmetic. Orange and red staining on fixtures and laundry, metallic taste, clogged plumbing. | SMCL: 0.3 mg/L (secondary) | An iron filter oxidizes and removes it. See how to test for iron and iron stains. |
| Manganese | Cosmetic and health. Black or brown staining; EPA notes neurological concerns at higher levels, especially for infants. | SMCL: 0.05 mg/L; health advisory 0.3 mg/L | The same iron and manganese filter usually handles both. Often travels with iron. |
| Total Dissolved Solids (TDS) | General chemistry. A snapshot of total mineral content. High TDS can mean salty taste or a sanity-check flag for deeper issues. | SMCL: 500 mg/L (secondary) | Investigate what is driving it. RO reduces TDS at the drinking tap when needed. |
If you only ever remember one rule, remember this tier. The National Ground Water Association makes the same core recommendation: test annually for bacteria, nitrate, and anything you have reason to suspect locally.
Tier 2: Test If You Have Symptoms
These contaminants usually announce themselves. If your water smells, tastes, or looks a certain way, add the matching test. Unlike the Tier 3 items, you often have a sensory clue that they are present, so they are easy to catch.
| Test This | The Symptom | Why It Matters | How to Fix It |
|---|---|---|---|
| Hydrogen Sulfide | Rotten egg smell, especially on the hot side | Cosmetic and nuisance. Corrosive to metals; makes water unpalatable. | Oxidizing filter or aeration; sometimes a carbon filter for light cases. See how to test for hydrogen sulfide. |
| Tannins | Yellow, amber, or tea-colored water | Cosmetic. Decaying organic matter; can stain laundry and fixtures, give an earthy taste. | A tannin filter (special anion resin) or oxidation, depending on the level. Send the result to Aidan to spec. |
| Sediment & Turbidity | Cloudy, gritty, or sandy water | Cosmetic and protective. Particles clog fixtures and shield bacteria from disinfection. | A sediment pre-filter sized to your particle load. Often the first stage in a whole-house system. |
| Copper | Blue-green stains on sinks and tubs | Health and infrastructure. Almost always caused by acidic water dissolving copper pipe. | Fix the cause: raise pH with an acid neutralizer. Test pH and copper together. |
| Chloride & Sodium | Salty or brackish taste | Health (sodium-restricted diets) and infrastructure. Can signal road salt, seawater intrusion, or a softener leak. | Reverse osmosis at the drinking tap removes sodium and chloride. |
No Symptom Does Not Mean No Problem
Tier 2 is symptom-driven, but the absence of a symptom is not a clean bill of health. Plenty of contaminants give zero warning. That is the entire point of Tier 3 below, and the reason a first-ever well test should be comprehensive rather than symptom-only.
Tier 3: Test Based on Geography and Risk
These are the dangerous ones, because most of them are invisible. No taste, no smell, no color, no stain. Whether you need to test for them depends on your local bedrock geology, nearby agriculture or industry, and the age of your plumbing. On a first-ever well test, most of these belong on the panel regardless, since you have no history to rule them out.
| Contaminant | Who Should Test & Why | EPA Limit | What a High Result Means & How to Fix It |
|---|---|---|---|
| Arsenic | Naturally occurring in bedrock across New England, the Mid-Atlantic, Upper Midwest, and Southwest. A Group 1 carcinogen. | MCL: 10 ppb (0.010 mg/L) | Ion-exchange or adsorptive arsenic system. See how to test for arsenic and the arsenic in well water guide. |
| Lead | Homes with pre-1986 plumbing, brass fixtures, or lead solder. No safe level for children. | Action level: 15 ppb (MCLG zero) | Corrosion control plus a certified lead filter such as the lead removal system or RO at the tap. See how to test for lead in drinking water. |
| Radon | Wells in granite/uranium-rich bedrock (New England, Appalachians, parts of the West). A radioactive gas. | No final federal MCL; EPA proposed 4,000 pCi/L | Aeration or granular activated carbon designed for radon. Specialized; test first. |
| Uranium | Same uranium-rich bedrock as radon. Chemical kidney toxicity plus radioactivity. | MCL: 30 ug/L (0.030 mg/L) | Anion exchange or RO. Often tested alongside radon and gross alpha. |
| Fluoride | Naturally occurring in some aquifers. High natural levels can damage teeth and bone. | MCL: 4.0 mg/L; SMCL 2.0 mg/L | RO or activated alumina. See fluoride in drinking water. |
| PFAS | Wells near industry, airports, military bases, or land where firefighting foam was used. "Forever chemicals." | EPA limit (public systems): 4 ppt PFOA/PFOS | A PFAS removal system using specialized media. See how to test for PFAS and the PFAS guide. |
| VOCs | Wells near fuel storage, dry cleaners, factories, or gas stations. Volatile organic compounds like benzene and TCE. | Varies by compound (e.g. benzene 5 ppb) | Whole-house activated carbon, sometimes with aeration. |
| Pesticides & Herbicides | Wells in or downhill from agricultural areas (atrazine, glyphosate, and others). | Varies by compound (e.g. atrazine 3 ppb) | Activated carbon filtration sized to the contaminant. Test if you are in farm country. |
| Gross Alpha / Radionuclides | A screening test for radioactivity; pairs with uranium and radon in affected regions. | MCL: 15 pCi/L (gross alpha) | RO or anion exchange depending on the specific radionuclide identified. |
Not sure which Tier 3 items apply to you? Your state geological survey and county health department track local hot spots, and the CDC recommends asking your local health department what contaminants are common in your area. When in doubt on a first test, include arsenic, lead, and uranium; they are the most common invisible offenders.
Build Your Well Water Test Checklist
Check the boxes that describe your situation. We will build a personalized list of what to test for, starting with the baseline every well needs and adding the symptom-driven and risk-based items that apply to you.
Your Situation
Contaminant to Treatment Bridge
Testing is only useful if it leads to action. This table connects what a test finds to what it causes in your home and how it gets fixed. Each fix links to the relevant guide or product cluster, so once your results come back you can go straight to the solution.
| If You Find... | What It Causes | How to Fix It |
|---|---|---|
| Coliform / E. coli | Health risk from bacteria and pathogens | UV disinfection or chlorination (see UV systems) |
| Iron / Manganese | Orange, red, brown, or black staining | Iron and manganese filter |
| Hardness | Scale, spotty dishes, dry skin, short appliance life | Water softener |
| Low pH (acidic) | Pipe corrosion, blue-green stains, pinhole leaks | Acid neutralizer |
| Hydrogen sulfide | Rotten egg smell, corroded metal | Oxidizing/iron filter or carbon filter |
| Nitrate | Health risk for infants, signals contamination source | Nitrate treatment or reverse osmosis |
| Arsenic | Long-term cancer and cardiovascular risk | Arsenic removal system |
| Lead / Copper | Neurological harm (lead), staining (copper) | Fix pH plus a lead removal system or RO at the tap |
| PFAS | Long-term health risk from "forever chemicals" | PFAS removal system |
| Sediment / turbidity | Cloudy water, clogged fixtures, shields bacteria | Sediment pre-filter (first stage of a whole-house system) |
| VOCs / pesticides / chlorine taste | Chemical taste and odor, health risk | Activated carbon (whole-house carbon) |
| Fluoride / uranium / nitrate at the tap | Various health concerns at drinking water | Reverse osmosis at the kitchen sink |
When several contaminants show up together (very common on Mid-Atlantic and Upper-Midwest wells), the order the equipment goes in matters. See our guide to the correct order of well water treatment systems so you do not foul one filter with the contaminant another should remove first.
Why You Test All of This at Once
Here is the point almost every "what to test for" article on the internet misses. You do not work down this checklist one test at a time. Ordering an iron test, then a bacteria test, then an arsenic test costs more in total and takes weeks longer than a single comprehensive panel, and it leaves you with disconnected numbers instead of a complete picture of your water chemistry.
That complete picture is what actually sizes treatment. To recommend the right iron filter, Aidan needs your iron, manganese, pH, and hardness together. To size an arsenic system, he needs arsenic plus pH, iron, and silica. Pull those numbers from five different one-off tests done months apart and they may not even reflect the same water. One panel, one sample, one snapshot.
Well Water Test Kit
- 53 contaminants in one sample
- Lead, arsenic, uranium, nitrate, fluoride
- Total coliform, E. coli, hardness, pH, iron, manganese
- NELAC/ELAP certified labs (SimpleLab network)
- Prepaid overnight return shipping
- Aidan reviews every result, no obligation
On City Water Instead?
- City Water Test Kit, 47 contaminants
- Lead at ppb by ICP-MS
- Free + total chlorine, chloramine
- Copper, arsenic, and more
- Same certified lab network and expert review
If you genuinely only need one contaminant measured (you already have a recent full panel and just want to recheck one thing), single-analyte kits exist for lead and copper, coliform and E. coli, PFAS, and fluoride. For a first test or an annual baseline, the full panel is almost always the better value. Compare the major lab kits in our best well water test kit guide, and see both options on the water testing collection.
"I'd had the water tested twice by different people and got two different numbers, one near zero and one around a hundred. I didn't know which to trust. Aidan told me the lab test was the accurate one and walked me through what each number actually meant for my equipment. That's when it clicked that I needed the whole panel, not just the one thing I was worried about."
Paraphrased from a recent customer call. Conflicting one-off readings are the single most common reason people call confused. A full certified panel ends the guessing and gives Aidan the numbers he needs to recommend the right system.
How Often to Test
This guide focuses on what to test for. For the step-by-step on how to collect a sample and run the test, see the pillar guide on how to test your well water. On frequency, the short version:
- Annually: the full Tier 1 baseline (coliform/E. coli, nitrate, pH, hardness, iron, manganese, TDS) every year.
- Once (then as needed): a comprehensive Tier 3 panel (arsenic, lead, uranium, radon, etc.) on a first-ever test, then periodically based on local risk.
- After any well work: new pump, deeper drilling, casing repair, or any service that opens the well.
- When something changes: new taste, smell, color, or cloudiness, or after a flood, drought, or heavy rainfall event.
- Real estate: before buying or selling a home with a well, using a certified lab result.
Once your results are in hand, our guide on how to read your well water test results walks through interpreting every number, or send the report to Aidan at 800-460-5810 and he will tell you what it means and what (if anything) it needs.
Frequently Asked Questions
What should I test my well water for?
At a minimum, test every private well at least once a year for total coliform bacteria and E. coli, nitrate, pH, hardness, iron, manganese, and total dissolved solids (TDS). Beyond that baseline, add symptom-driven tests (hydrogen sulfide if you smell rotten eggs, copper if you see blue-green stains, tannins for yellow water) and risk-based tests (arsenic, lead, radon, uranium, fluoride, PFAS, and pesticides) depending on your local geology, plumbing age, and land use. On a first-ever test, run a comprehensive panel so you have a complete baseline.
What is included in a well water test?
A comprehensive well water test panel includes bacteria (total coliform and E. coli), inorganic chemistry (nitrate, fluoride, chloride, sulfate, sodium, TDS), metals (iron, manganese, arsenic, lead, copper, uranium), physical properties (pH, hardness, turbidity), and often radiological screening (gross alpha). Our Well Water Test Kit covers 53 contaminants in one sample through NELAC and ELAP certified labs. Basic kits cover fewer parameters; single-analyte kits test just one contaminant.
How often should well water be tested?
Test the core baseline (coliform, nitrate, pH, and the common minerals) at least once a year, which is what the CDC and EPA recommend for every private well. Run a broader panel including arsenic, lead, and uranium on a first-ever test, then periodically based on local risk. Always retest after any well work, after a noticeable change in taste, smell, color, or pressure, after a flood or drought, and before buying or selling a home with a well.
What contaminants are most common in well water?
The most common findings on private wells are hardness (calcium and magnesium), iron and manganese (staining), low pH (acidic, corrosive water), and bacteria from surface contamination. Nitrate is common in agricultural areas. Arsenic is widespread in certain bedrock regions (New England, the Mid-Atlantic, the Upper Midwest, and the Southwest). Which ones you have depends heavily on your local geology and land use, which is exactly why testing matters more than assuming.
Do I need to test for bacteria every year?
Yes. The CDC, EPA, and the National Ground Water Association all recommend testing every private well for total coliform bacteria at least once a year, and immediately any time you notice a change in taste, color, or smell, after any well repair, or after flooding. Bacteria contamination can appear suddenly when surface water finds a path into the well, and there is no taste or smell to warn you, so annual testing is the only reliable safeguard.
How can I tell if my well water is making me sick?
You often cannot tell from symptoms alone, which is the danger. Bacteria like E. coli can cause gastrointestinal illness, high nitrate is dangerous to infants, and contaminants like arsenic and lead cause long-term harm with no immediate symptoms at all. None of the most serious contaminants (arsenic, lead, nitrate, radon, uranium) produce a taste, smell, or color you would notice. The only reliable way to know your water is safe is a certified laboratory test covering the contaminants in this checklist.
Can I test my well water at home, or do I need a lab?
At-home strip kits give a rough screen for a few parameters (hardness, pH, sometimes iron or nitrate), but they are not accurate enough for the health-critical contaminants. Bacteria, arsenic, lead, nitrate, uranium, and PFAS all require a certified laboratory test to get a number you can act on. A mail-in kit like the Well Water Test Kit gives you lab-grade results from a NELAC/ELAP certified lab while letting you collect the sample yourself at home.
How much does it cost to test well water?
A single-contaminant lab test typically runs $20 to $90. A comprehensive panel covering 50+ contaminants runs roughly $150 to $300; our Well Water Test Kit is $199 for 53 contaminants. Many state health departments and cooperative extension offices offer free or low-cost testing for specific contaminants like nitrate, bacteria, or arsenic. For a first test or annual baseline, a full panel almost always costs less than ordering several single tests separately.
Not sure what your results mean? Once you have a certified lab panel in hand, Aidan can read it and tell you exactly what (if anything) your water needs in about 5 minutes. Email your results to support@midatlanticwater.net or call Aidan directly at 800-460-5810. There is no obligation, no hard sell, and no charge for the recommendation.
Written by Aidan Walsh, owner of Mid Atlantic Water. 32+ years installing well water treatment systems across Pennsylvania, Maryland, Delaware, New Jersey, Virginia, and beyond. Article reviewed June 2026.