Testing a Private Well in the Finger Lakes: What to Test, How Often, and What to Do After a Flood

Last reviewed: October 21, 2026. General information only, not medical or legal advice. Testing recommendations and standards here come from the New York State Department of Health (DOH) and the Department of Environmental Conservation (DEC). Your local health department can advise on your specific well.

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Outside the cities and villages, a lot of Finger Lakes homes get their water from a private well, and some lakeshore homes draw straight from the lake. Unlike a public water system, nobody tests a private well for you. Statewide, New York has no routine testing requirement for an existing private well, so whether the water in your kitchen is safe depends on what you check and how often.

This regional guide explains what the State Health Department recommends testing, how often, how to find a certified lab, what the results mean, what to do after a flood or a bad result, how to disinfect a well, and what to check when you buy a house with a well. It belongs to our Septic and Wells section. For lake-by-lake detail, see the local guides listed near the end.

How often should you test a private well?

The DOH’s short version: test your water at the tap at least once a year for bacteria, and every 3 to 5 years for other contaminants. It says the best time to test is late spring or early summer, and that the lab will provide instructions and sample bottles.

The DOH’s “Test Your Well” schedule:

Test for	Why it matters	How often
E. coli and coliform bacteria	Signal possible fecal contamination; can cause diarrhea and vomiting	Every year
Lead	Harms many organs and systems; most harmful to babies and young children	Every 3 to 5 years
Nitrate and nitrite	Most harmful to babies; linked to infant blood problems	Every 3 to 5 years
Arsenic	Long-term exposure linked to cancer and other health effects	Every 3 to 5 years
Sodium	Concern for people on restricted-sodium diets	Every 3 to 5 years
Iron and manganese	Rust or black staining of fixtures and laundry	Every 3 to 5 years
Turbidity (cloudiness)	Interferes with chlorine and UV disinfection	Every 3 to 5 years
pH, hardness, alkalinity	Pipe corrosion, scale, taste, and treatment problems	Every 3 to 5 years

When to test outside the schedule

The DOH also recommends testing when:

• The water’s look, smell, or taste changes.
• Your household changes, such as a pregnancy, a new baby, or a change in someone’s health.
• You or your doctor suspect the water is causing symptoms such as diarrhea or vomiting.
• You’ve had repairs to the well, pipes, or house, or changed your water system. Test for E. coli and coliform after any disinfection or maintenance, too.
• There are land-use changes nearby, such as construction or farming that could send runoff toward the well.
• Your well was flooded or damaged by extreme weather.
• The well runs dry or the flow at your faucets changes.

In farm country, which describes much of the Finger Lakes, the nitrate test deserves attention if anyone in the house is pregnant or there’s an infant, since the DOH says nitrate is most harmful to babies.

What the results mean

Use a lab certified for drinking water (see the next section), and compare the results with the DOH’s recommended limits for residential wells. These come from DOH Fact Sheet 3 and are based on public water supply standards:

• Coliform bacteria: any positive result is a concern. It indicates possible disease-causing contamination.
• Nitrate: 10 mg/L (as nitrogen). Nitrite: 1 mg/L (as nitrogen).
• Arsenic: 0.01 mg/L.
• Lead: 0.015 mg/L.
• Iron: 0.3 mg/L. Manganese: 0.3 mg/L. Iron plus manganese: 0.5 mg/L.
• Turbidity: 5 NTU.
• Chloride and sulfate: 250 mg/L each (salty taste and laxative effect, respectively).
• Sodium: no set limit, but the DOH says water above 20 mg/L shouldn’t be used for drinking by people on severely restricted sodium diets, and above 270 mg/L by people on moderately restricted diets.
• pH, hardness, alkalinity: no designated limits, but they affect corrosion, scale, taste, and treatment.

If tests show contamination, the DOH’s advice is to stop using the water for drinking, preparing food, and making ice, switch to bottled water, and work through its “restore your well” steps: check the well and surrounding area for damage, repair and flush the well, disinfect it for biological contamination, and retest.

If you suspect gasoline, heating oil, or chemicals, call your health department and the DEC Spill Hotline at 800-457-7362. The DOH warns that boiling or disinfecting water will not remove oil and other chemicals. That’s one reason to keep an old heating oil tank in good shape.

Finding a certified lab and taking the sample

The DOH says samples should be analyzed by a lab certified through its Environmental Laboratory Approval Program (ELAP) for potable (drinking) water. You can search the state’s ELAP laboratory directory: choose the potable water category and the tests you need, then call a few labs about price, sample bottles, and how quickly they need the sample back. Bacteria samples usually have a short holding time, so plan the pickup or drop-off before you fill the bottle.

A few sampling habits make results more useful:

• Follow the lab’s bottle and handling instructions exactly.
• Sample at the tap you drink from, as the DOH recommends, unless the lab says otherwise.
• If you’ve just shock-chlorinated, wait until the chlorine is fully flushed before a bacteria test (see the disinfection steps below).
• Keep every result with the date in one folder. The DOH recommends keeping records of testing and maintenance, and buyers will ask for them later.

Who to call: health departments around the Finger Lakes

Some counties handle private well questions through their own health departments; others are covered by a State Health Department district office. According to the DOH’s district office list:

• Ontario, Wayne, and Yates counties: NYSDOH Geneva District Office, (315) 789-3030.
• Schuyler and Steuben counties: NYSDOH Hornell District Office, (607) 324-8371.
• Other Finger Lakes counties (for example Seneca, Cayuga, Tompkins, Onondaga, and Livingston) aren’t on that list; start with your county health department.

The DOH’s Private Well Risk Mapper lets you type in an address and see potential risks around it, including flooding, agricultural runoff, naturally occurring arsenic, and bedrock conditions. It’s a good first look before you choose which optional tests to add.

After a flood: restoring and disinfecting a well

Flooding is the classic way a well gets contaminated, and it’s not just lakeshore homes; creeks and gullies flood across the region (see our Finger Lakes flood zones guide). The DOH says a flooded well should be disinfected before you use the water for washing, drinking, or cooking, and that you should use bottled water or other safe water until a test shows the well is safe.

Safety first. Electricity and water are a dangerous mix. The DOH says to shut off power to the pump, check for damaged wire insulation or missing wire nuts, and wear waterproof, rubber-soled boots before you do anything to the well.

The DOH’s 12-step method, in brief:

1. Attach a hose to the outdoor faucet nearest the well or pressure tank and run it until the water is clear.
2. Mix 2 quarts of regular, unscented household bleach in 10 gallons of water. Don’t use splashless, scented, or gel bleach.
3. Turn off power to the pump, then carefully remove the well cap (and seal, if there is one).
4. Turn the pump power back on, put the hose into the casing, and open the faucet.
5. Pour the bleach mixture down the casing while the hose keeps running.
6. Run every indoor and outdoor faucet until you smell chlorine, then shut each one off (except the hose).
7. Keep the hose running into the casing to recirculate the solution and wash down the inside of the casing.
8. After one hour, remove the hose and make sure all faucets are off so the pump stops.
9. Mix 2 more quarts of bleach in 10 gallons of water; use about half a gallon to disinfect the cap and seal, turn off the pump power, pour the rest into the well, and replace the cap.
10. Let the well sit at least 8 hours, preferably 12 to 24, with the pump power off.
11. Turn the power back on.
12. Flush the chlorinated water through a hose away from grass and shrubs until the chlorine smell is gone, then run every faucet until the smell disappears.

Then test for bacteria once the chlorine is gone. The DOH recommends hiring a water well contractor to disinfect a point well or a well with a jet pump. Our sister guides on Keuka well water and wells and septic outside Hornell cover local well types.

Routine well maintenance

The DOH’s maintenance checklist (Fact Sheet 7) suggests checking these items every year:

• Casing: free of holes and cracks, and at least 12 inches above the ground.
• Cap: no cracks, securely attached, with a screened vent. Don’t remove it except for maintenance such as disinfection.
• Pressure tank: gauge working and pressure in its normal range (the DOH notes typically 30 to 60 psi).
• Ground around the well: sloping away from the casing, no pooled water, no debris piled against it.
• Nearby hazards: no household chemicals or animal wastes within 100 feet of the casing, and above-ground oil tanks in good condition, watched while being filled.
• Septic: look for surface breakouts, and have the tank pumped or inspected every 2 to 3 years by a DEC-permitted waste transporter. Our New York septic rules guide covers the regional rules.

The DOH also suggests an annual inspection by a DEC-registered well contractor. If you have treatment equipment (a softener, filter, or UV light), follow the manufacturer’s maintenance schedule, since the DOH warns that neglected systems can fail.

Hiring a well driller or pump contractor

New York’s Environmental Conservation Law section 15-1525 requires any business that drills water wells to register with DEC every year. Registrations run through March 31 of the following year, and drilling and pump work must be supervised on site by someone who has passed the required exams. DEC’s consumer guide adds that pump contractors must be registered and certified if they open the well, and that the State Building Code requires wells to be drilled by a registered contractor.

Before you hire, DEC’s consumer protection checklist suggests:

• Check the contractor with DEC’s registered water well contractor search.
• Get more than one estimate, ask for references, and call them.
• Confirm insurance and get a written contract.
• Ask your local health and building code officials about local requirements. DEC says a state permit generally isn’t needed (outside some Long Island and deep geothermal cases), but some counties require a local permit.
• For a new well, get the Water Well Completion Report. The driller must file it with DEC and give you a copy. DEC also publishes completion report data, so you can look up the depth and yield of nearby wells.

Buying a Finger Lakes house with a well

New York’s Property Condition Disclosure Statement asks sellers whether the water quality or flow rate has been tested, but a seller’s answer isn’t a test. Before you close:

1. Ask for any past test results and the well’s completion report, if one exists.
2. Order your own test from an ELAP-certified lab: at minimum bacteria, plus nitrate and the other DOH 3-to-5-year tests if there are no recent results. Add tests the Risk Mapper or a neighbor’s experience suggests.
3. Ask for a flow or yield test if water quantity matters to you, especially for a larger household or a house that was used seasonally.
4. Have the well cap, casing, pressure tank, and any treatment equipment looked at; a standard home inspection may only glance at them.
5. Check the distance to the septic system and any fuel tanks.

Lake-specific detail lives on our local sites:

• Keuka: Well water around Keuka Lake, drinking water from the lake vs. wells, and lead pipes and water testing
• Seneca: Seneca Lake drinking water, intakes, wells, and algal blooms
• Canandaigua: Canandaigua Lake drinking water and algal blooms and septic inspections
• Hornell and the Southern Tier: Private wells and septic outside Hornell

What to have on hand

Inexpensive items that help with the maintenance and disinfection steps above (links go to Amazon search results). None of them replaces a certified lab test:

• Sanitary well caps with a screened vent if yours is cracked or loose (match your casing size)
• Chlorine test strips to confirm the chlorine is flushed out before a bacteria test
• Water pressure gauges if the gauge at your pressure tank has failed

Frequently asked questions

Official sources

• NYSDOH: Private Wells
• NYSDOH: Test Your Well: Protect Your Family’s Water
• NYSDOH Fact Sheet 3: Recommended residential water quality testing
• NYSDOH Fact Sheet 7: Checklist for testing, operation, and maintenance of residential wells (PDF)
• NYSDOH: Restoring Your Private Well
• NYSDOH: Restoring and Testing Your Private Well After a Flood
• NYSDOH: Private Well Risk Mapper
• NYSDOH: ELAP laboratory search
• NYSDOH: District Environmental Health Programs
• NYSDOH press release: private well testing (March 2024)
• NYSDEC: Water Well Contractor Program
• NYSDEC: Water Well Consumer Protection Guide (PDF)
• NYS Department of State: Property Condition Disclosure Statement (PDF)

Related on Practical Finger Lakes: New York septic rules basics · Finger Lakes flood zones and flood insurance · Winter driving and road access

Across the network: For pump and pressure tank trouble, Living on Keuka explains warning signs, NY rules for pump replacement, and dry wells.