How do I know if my well water is safe to drink?

You cannot tell by look, taste, or smell. USGS Circular 1332: contaminants in domestic wells are often invisible in the glass. EPA does not regulate private-well tap water the way it regulates public systems, so the owner must test. CDC's yearly floor is total coliform and nitrate at a state-certified lab, plus TDS and pH. Bacteria or nitrate still goes to the local health department.

How do I test if my well water is safe to drink?

Order bottles from a state-certified drinking-water lab. Start at certified labs by state. CDC's yearly floor is total coliform, nitrates, TDS, and pH. Sample the untreated tap the way the bottle says. A store strip cannot replace the bacteria or nitrate record. If either line fails, take the sheet to the local health department.

If I boil my well water, is it safe to drink?

Boiling kills germs. CDC: if you cannot get other water, boiling kills germs. CDC also: boiling will not remove chemicals from water. Minnesota Department of Health: boiling water that also has nitrate or arsenic can concentrate those chemicals. If coliform is present, use other water and call the health department. If nitrate is high, do not boil as a fix.

My well water smells like sulfur, is it safe to drink?

A boiled-egg smell is hydrogen sulfide. EPA's odor SMCL is an aesthetic guide, not a bacteria or nitrate result. Smell does not replace the certified-lab pair. See rotten-egg smell in well water. Test coliform and nitrate at a state-certified lab. If either line fails, take the sheet to the local health department.

How can you tell if your well water is bad?

You cannot tell from a clear glass. USGS Circular 1332: contaminants in domestic wells are often invisible. A change in taste, smell, or color is a reason to test now (CDC and EPA), not a diagnosis. The only answer is a certified-lab sheet. Bacteria or nitrate still goes to the health department.

How do I make sure my well water stays safe to drink?

Test every year at a state-certified lab. CDC and EPA put total coliform, nitrates, TDS, and pH on that yearly floor. Test again after flooding, well work, or a change in taste, smell, or color. See how often to test well water. Extra tests follow the house and the geology. Bacteria or nitrate still goes to the local health department.

Guide · Updated October 21, 2026

Is my well water safe to drink?

Direct answer

You cannot tell by look, taste, or smell. EPA does not regulate private wells the way it regulates public systems, so the owner must test. At minimum, test coliform bacteria and nitrate at a state-certified lab, then local concerns such as arsenic or lead. Bacteria or nitrate still goes to the local health department.

What to test
What to test	Why	EPA MCL / SMCL or guidance
Total coliform	CDC’s annual floor for a private well. A present result is a pathway warning, not a shopping trip.	Present/absent: any detected coliform is a positive until a clean retest CDC well-testing guidelines
Nitrate as N	Same yearly panel as coliform. A result at or above the public-system line goes to the health department.	10 mg/L as N (EPA public-system MCL) EPA National Primary Drinking Water Regulations
pH	CDC annual floor. Low pH is a corrosion clue, not an iron-filter job.	6.5–8.5 SMCL (aesthetic guideline) EPA secondary standards
Total dissolved solids	CDC annual floor with coliform, nitrate, and pH.	500 mg/L SMCL (aesthetic guideline) EPA secondary standards

What to circle on the sheet

A teaching diagram, not a lab form. Circle these names on your real report. Bacteria or nitrate still goes to the health department.

Iron
Orange or rust stains. Secondary (aesthetic) number is 0.3 mg/L. Treatment class, not a health-department line.
Manganese
Brown to black stains. Secondary number is 0.05 mg/L. Often travels with iron.
H2S
Rotten-egg odor. The gas often leaves a mailed bottle. Trust the nose; ask for a field kit if you need a number.
Coliform
Presence or absence. Health department. This site will not turn that line into a filter shopping list.
Nitrate
Compared to 10 mg/L as N. Health department. Not a softener or iron-filter problem.

A clear glass is not a result. This page is a safety check, not medical advice.

Steps

Do not decide from look, taste, or smell. USGS Circular 1332: contaminants in domestic wells are often invisible in the glass. EPA's odor SMCL (3 TON) is an aesthetic guide. Iron at 0.3 mg/L and manganese at 0.05 mg/L are also secondary, nuisance lines, not a bacteria or nitrate pass.
Order bottles from a state-certified drinking-water lab. CDC's yearly floor is total coliform bacteria, nitrates, total dissolved solids, and pH. EPA's Protect Your Home's Water page prints the same four. Then add local concerns: arsenic where the rock can carry it, lead if the solder is old, radon or uranium where the state names them, and PFAS only as a certified-lab panel.
Sample the untreated tap the way the lab printed on the bottle. Bacteria has a hold time. A Friday drop-off that sits over a weekend is often void.
Read the sheet. Circle total coliform, E. coli, nitrate, and nitrite first. Units and "ND" live on how to read a well water lab report.
If coliform is present, or nitrate is at or above 10 mg/L as N (EPA's public-system MCL), take the sheet to the local or state health department. See coliform bacteria in well water and nitrates in Wisconsin well water. State nitrate pages also exist for Iowa, Minnesota, and Texas.
Well water test kits can screen iron, hardness, or pH the same day. They cannot replace the yearly bacteria or nitrate record.

When to test

The yearly cadence, and the extra-test list, is how often should you test your well water. Do not wait for the anniversary if any of these happen. CDC and EPA both print an extra-test list.

Flooding, land disturbance, or a nearby waste site. If floodwater reached the wellhead, do not start here. Start with Well flooded? What to test and when.
Well repairs, a new pump, or other well-system work. CDC: test after you replace or repair any part of the well system.
A change in taste, smell, or color. CDC and EPA both treat that change as a reason to test now. A sulfur or boiled-egg odor is rotten-egg smell in well water. The smell is not a bacteria or nitrate result.
Nearby septic problems, construction, or a new industrial neighbor. EPA: test when conditions near the well change, including new construction or industrial activity.
Pregnancy, nursing, or a child in the home. CDC: test if you or someone you live with becomes pregnant, or if a child starts living with you.
Buying a house with a well. EPA's private-well pages still put testing on the owner. Use a state-certified lab, not a store strip.

CDC also says to check the well itself every spring for mechanical problems. That is a wellhead look, not a substitute for the lab sheet.

State lab links

Use a laboratory certified for drinking water in your state. Start at certified labs by state, then the inventory that matches the house:

Arsenic pages for the same states live at Maine, Minnesota, Texas, and Wisconsin. Those are local extras. They do not cancel CDC's yearly bacteria and nitrate pair.

What the results mean

CDC: if the result shows harmful germs or chemicals, do not drink the water until it is treated. Use bottled water or another safe source, and contact the local health or environmental department. That department can help you read the sheet. This site will not turn a number into a diagnosis.

Total coliform present, or E. coli present. Use other water. Call the local health department. The reading order is coliform bacteria in well water.
Nitrate at or above 10 mg/L as N. That is EPA's public-system MCL, used here as a comparison line. Take the sheet to the health department. Do not treat a high nitrate as a filter-shopping trip.
Boiling. CDC's treating page: if you cannot get other water, boiling kills germs. CDC also: "Boiling will not remove chemicals from water." Minnesota Department of Health's bacterial-safety page: boiling water that also has nitrate or arsenic can concentrate those chemicals. Boiling is not a nitrate fix, and it is not an arsenic fix.
A stain, a sulfur smell, or a clear glass. Those are not the yearly pair. Iron, manganese, and odor have EPA secondary (nuisance) lines. Arsenic, lead, and PFAS need their own certified-lab methods.

After the sheet comes back

Official certified-lab and health-department paths come first. Tap Score / SimpleLab is a class example of a mail-in certified-lab kit, not a ranked pick (Awin tracked URL). Well Diagnosis may earn a commission if you buy through an approved affiliate link on this page. That does not change the price you pay. See the disclosure. SoftPro is not on this page. Bacteria or nitrate still goes to the health department.

FAQ

How do I know if my well water is safe to drink?: You cannot tell by look, taste, or smell. USGS Circular 1332: contaminants in domestic wells are often invisible in the glass. EPA does not regulate private-well tap water the way it regulates public systems, so the owner must test. CDC's yearly floor is total coliform and nitrate at a state-certified lab, plus TDS and pH. Bacteria or nitrate still goes to the local health department.
How do I test if my well water is safe to drink?: Order bottles from a state-certified drinking-water lab. Start at certified labs by state. CDC's yearly floor is total coliform, nitrates, TDS, and pH. Sample the untreated tap the way the bottle says. A store strip cannot replace the bacteria or nitrate record. If either line fails, take the sheet to the local health department.
If I boil my well water, is it safe to drink?: Boiling kills germs. CDC: if you cannot get other water, boiling kills germs. CDC also: boiling will not remove chemicals from water. Minnesota Department of Health: boiling water that also has nitrate or arsenic can concentrate those chemicals. If coliform is present, use other water and call the health department. If nitrate is high, do not boil as a fix.
My well water smells like sulfur, is it safe to drink?: A boiled-egg smell is hydrogen sulfide. EPA's odor SMCL is an aesthetic guide, not a bacteria or nitrate result. Smell does not replace the certified-lab pair. See rotten-egg smell in well water. Test coliform and nitrate at a state-certified lab. If either line fails, take the sheet to the local health department.
How can you tell if your well water is bad?: You cannot tell from a clear glass. USGS Circular 1332: contaminants in domestic wells are often invisible. A change in taste, smell, or color is a reason to test now (CDC and EPA), not a diagnosis. The only answer is a certified-lab sheet. Bacteria or nitrate still goes to the health department.
How do I make sure my well water stays safe to drink?: Test every year at a state-certified lab. CDC and EPA put total coliform, nitrates, TDS, and pH on that yearly floor. Test again after flooding, well work, or a change in taste, smell, or color. See how often to test well water. Extra tests follow the house and the geology. Bacteria or nitrate still goes to the local health department.

State pages and the labs hub

Sources

1.CDC. Guidelines for Testing Well Water.
2.CDC. Guidelines for Treating Well Water.
3.U.S. EPA, Private Wells. Protect Your Home’s Water.
4.U.S. EPA. Private Drinking Water Wells.
5.U.S. EPA. National Primary Drinking Water Regulations.
6.U.S. EPA. Secondary Drinking Water Standards: Guidance for Nuisance Chemicals.
7.U.S. Geological Survey. Quality of Water from Domestic Wells in Principal Aquifers of the United States, 1991–2004 (Circular 1332).
8.Minnesota Department of Health. Bacterial Safety of Well Water.