When you buy a Southern New Hampshire home with a private well, you are not just evaluating the house. You are also evaluating the home's water source.

The practical answer is simple: order laboratory testing early, use New Hampshire Department of Environmental Services guidance, confirm that the laboratory is accredited for the tests you need, and evaluate the physical well system separately from water quality. Clear, good-tasting water is reassuring, but it is not a laboratory result.

This does not mean a private well should make you nervous. Many well-served homes are excellent choices. It does mean that your inspection plan should answer the right questions while your contract still gives you time to make a thoughtful decision.

Water quality and water supply are two different questions

Buyers often say they want to “test the well,” but that phrase can describe two separate evaluations.

The first is water quality. A laboratory analyzes a properly collected sample for specific contaminants or characteristics. The second is water supply and equipment condition. A qualified inspector or well professional can evaluate visible components such as the well cap, pressure tank, gauge, controls, piping, and treatment equipment, and can discuss an appropriate way to assess flow or recovery for that property.

A clean laboratory report does not prove that a pump, pressure tank, or treatment system is in good condition. A strong shower does not prove that the water is free of arsenic, bacteria, PFAS, radon, uranium, or other substances. Your due-diligence plan should address both sides.

Start with New Hampshire's testing guidance

The New Hampshire Department of Environmental Services, commonly called NHDES, publishes a private-well testing fact sheet and maintains a private-well resource page. Its standard analysis includes arsenic, bacteria, chloride, copper, fluoride, hardness, iron, lead, manganese, nitrate or nitrite, pH, sodium, and uranium. NHDES also identifies separate radiological testing that includes radon, uranium, and analytical gross alpha, and it provides guidance on volatile organic compounds.

NHDES has advised private-well owners to test bacteria and nitrate annually and to repeat broader testing on a three-to-five-year schedule. A home purchase is a logical time to establish your own baseline, especially when the seller's report is old, limited, or unavailable.

Do not assume that every “water test” is the same. A basic bacteria test is not the same as the broader standard analysis. Ask the laboratory for the exact analyte list in writing so you know what the package includes and what it leaves out.

Why arsenic deserves specific attention in New Hampshire

Arsenic is naturally occurring and cannot be identified by appearance, smell, or taste. In 2021, NHDES reported that it estimated 25% to 30% of New Hampshire private residential wells had arsenic at or above 5 parts per billion, the state's enforceable limit for public water systems.

That historical state estimate is a strong reason to make arsenic testing routine rather than optional. It is not a prediction about a particular property. Only a properly collected sample analyzed by a qualified laboratory can tell you what is present in the water from the home you are considering.

If arsenic is detected, avoid choosing treatment from a generic online recommendation. The appropriate response depends on the concentration, water chemistry, household needs, where treatment should occur, and how the system will be maintained. Use the laboratory report and NHDES resources, then obtain advice and written proposals from qualified water-treatment professionals.

Ask about PFAS, radiological testing, and property-specific concerns

PFAS are a large group of long-lasting manufactured chemicals. NHDES maintains a dedicated PFAS response site and has provided testing for private wells considered susceptible to contamination. The U.S. Environmental Protection Agency notes that many PFAS break down very slowly and can build up in people, animals, and the environment.

For a buyer, the right question is not whether every property needs every possible test. It is whether your test plan reflects current state guidance, the property's location and history, nearby land uses, lender requirements, and your own risk tolerance. Ask the laboratory whether PFAS is included or must be ordered separately. Do the same for radon in water, gross alpha, volatile organic compounds, and any other add-on the lab or qualified professional recommends for the site.

This is also where local knowledge matters. A standard package is a starting point, not a substitute for reviewing the actual property.

Control the sample and the timeline

The most useful report is one you can trust and receive in time to act on it. Before the inspection period begins to run, confirm:

    
1. Who will collect the sample.
    
2. Which laboratory will analyze it.
    
3. Whether that laboratory is accredited for the requested methods.
    
4. The complete list of tests ordered.
    
5. Whether the sample will be taken before or after existing treatment equipment.
    
6. The laboratory's current turnaround time.
    
7. How the results will be delivered to the buyer.
  

Follow the laboratory's collection instructions. Different tests can require different containers, preservation methods, handling, or timing. A casual sample poured into a household jar is not a substitute for the lab's procedure.

Sampling location matters too. A sample taken after a treatment system tells you about treated water at that tap. A sample taken before treatment helps describe the source water. Depending on the property and your objectives, you may need to understand both. Label the reports clearly so there is no confusion later.

Inspect the well system, not just the water

A home inspector may comment on visible conditions, but well systems are specialized. Ask what the inspection covers and whether a separate well professional is appropriate.

    
• Where is the well head, and is it accessible?
    
• Is the cap secure and the area properly graded?
    
• What is known about the well's age, depth, construction, and service history?
    
• What condition are the pump, pressure tank, controls, gauge, and visible piping in?
    
• Is there water-treatment equipment, and who maintains it?
    
• Are there service records, warranties, filter-change logs, or prior laboratory reports?
    
• What method will be used to evaluate the home's water supply under realistic demand?
  

No single visual clue answers all of these questions. The goal is a documented picture of the source, equipment, performance, and water quality.

What to do when a result is above a guideline or standard

An unfavorable result is a decision point, not automatically the end of the purchase. Start by asking the laboratory to explain the report and whether confirmation sampling is appropriate. Use the NHDES Be Well Informed tool to help interpret common results, and consult qualified professionals about treatment, installation, maintenance, and retesting.

    
• Is the issue treatable at the point of use, at the point where water enters the home, or not easily treatable?
    
• What equipment, electrical work, plumbing, space, and drainage would be required?
    
• What are the ongoing filter, media, testing, and service needs?
    
• Will the proposed solution satisfy any lender or insurance requirement that applies?
    
• When will corrective work be completed, and how will performance be verified?
  

Your options depend on the purchase contract and the facts. A buyer might request corrective work, seek a credit or price adjustment, accept the condition with a plan, or exercise a contractual right to withdraw. Coordinate with your real estate agent and, when appropriate, your lender and attorney before deadlines expire.

A calm pre-closing checklist

    
1. Identify the water source and visible well equipment before making assumptions.
    
2. Put the inspection and testing scope into the purchase strategy.
    
3. Order the lab work promptly after the contract is signed.
    
4. Use an accredited laboratory and follow its sampling instructions.
    
5. Compare the ordered panel with current NHDES guidance.
    
6. Evaluate physical equipment and water supply separately.
    
7. Review reports with qualified professionals, not just the seller or listing sheet.
    
8. Obtain written treatment or repair proposals when needed.
    
9. Make decisions before contractual deadlines.
    
10. Keep the reports, invoices, manuals, and retest results for future maintenance.
  

Private-well due diligence is not about finding a perfect report. It is about replacing uncertainty with usable information. When the testing plan is set early, buyers have more room to compare options, price solutions, and protect the closing timeline.

If you are considering a home with a private well in Salem, Windham, Pelham, Atkinson, Hampstead, Derry, Londonderry, or another Southern New Hampshire community, I can help you build the right questions into your purchase plan and coordinate the real estate side of the process with your chosen inspectors and specialists.

This article is for general educational purposes and is not environmental, medical, legal, lending, or water-treatment advice. Testing scope, contract rights, and professional requirements vary by property. Consult NHDES, an appropriately accredited laboratory, qualified well and treatment professionals, your lender, and your attorney as applicable.