What a Standard Inspection Covers vs. What Water Testing Covers
During a home inspection, your inspector will visually assess the well components. That includes checking the wellhead for proper sealing and clearance from the ground surface, inspecting the pressure tank for correct pressure settings and evidence of waterlogging, and running water fixtures to confirm adequate flow and pressure throughout the house.
What an inspector cannot do is tell you anything about what's in the water. Bacteria, nitrates, arsenic, lead, volatile organic compounds — none of that is visible. Determining water quality requires collecting a water sample and sending it to a certified laboratory for analysis.
Water testing is separate from the inspection and involves a separate fee, usually $75 to $300 depending on how many parameters you're testing. Some inspectors are certified to collect samples; others will recommend you hire a separate water testing service or contact your state's certified lab list directly.
Which Tests to Order
The minimum test for any private well is a basic bacteriological analysis — specifically testing for total coliform bacteria and E. coli. These are the most common contaminants in private wells and the ones most directly tied to health risk. The CDC recommends testing well water at least once a year for bacteria, more often if you notice changes in taste or smell.
Beyond bacteria, what else you should test for depends heavily on where the property is located and what the surrounding land has been used for. A few categories to consider:
Nitrates
Nitrate contamination is common in agricultural areas, near livestock operations, or on properties that have had septic systems for many years. High nitrate levels are particularly dangerous for infants. The EPA's maximum contaminant level for nitrates in drinking water is 10 mg/L.
Heavy Metals
Arsenic occurs naturally in the bedrock in many parts of the country, particularly in New England, the Great Plains, and parts of the Southwest. Lead can leach from older plumbing components even if the well water itself is clean. If the home has galvanized or lead service lines, testing for lead at the tap is worthwhile regardless of well depth.
Volatile Organic Compounds (VOCs)
If the property is near industrial sites, dry cleaners, gas stations, or areas with known groundwater contamination, VOC testing is worth adding. Common VOCs like trichloroethylene (TCE) and benzene are serious health concerns at elevated levels. Your state environmental agency can often tell you about known contamination sites in a given area.
Radon in Water
In regions with high radon-in-air levels, testing dissolved radon in well water is also recommended. Radon can off-gas from water during showering or dishwashing, contributing to indoor air radon levels. This is a separate test from radon in air and is often added for an additional fee.
How to Order Testing and What the Timeline Looks Like
The most important thing to know about timing: water test results take 3 to 5 business days after the lab receives the sample. If your inspection contingency is only 7 to 10 days, you need to get this moving on day one.
To get started, either ask your inspector if they offer water sampling as an add-on, or find a certified lab through your state's health department website. Many states maintain a list of certified labs on their environmental or health department sites. The EPA publishes a guide on how to get your well tested, including how to find state-certified labs.
The sample is collected from a cold water tap inside the house — usually the kitchen faucet — following specific protocols to avoid contaminating the sample. The kit typically includes sterile bottles and instructions. You or the inspector follow the collection procedure, seal the samples, and ship or drop them off at the lab within a specified time window (usually same day or overnight).
Results come back as a lab report listing each parameter tested, the detected level, and the EPA maximum contaminant level (MCL) for comparison. Most results are straightforward to read: either below the MCL (acceptable) or above it (requires action).
What Happens If Results Come Back With Problems
Failed bacteria tests are the most common finding, and they're often fixable. Shock chlorination — essentially flushing the well with a diluted bleach solution — resolves many coliform findings, particularly if the contamination is recent or tied to surface infiltration. This costs roughly $300 to $600 and is usually done by a well service company. After treatment, the well is retested to confirm the bacteria has been eliminated before the home closes.
More complex contamination issues are harder to resolve:
Arsenic and Heavy Metals
Point-of-use reverse osmosis systems remove arsenic and most heavy metals effectively and cost $300 to $800 installed. Whole-house filtration with arsenic-specific media runs $1,500 to $3,000. These are permanent installations. The buyer should understand this is an ongoing maintenance commitment — filters need replacement, and systems need annual servicing.
Nitrates
Reverse osmosis also removes nitrates. If the contamination source is an old or failing septic system on the property, remediation is more complicated and expensive — a septic repair or replacement is a separate negotiation entirely.
VOC Contamination
If VOCs are detected above MCLs, this is a significant finding that may indicate off-site contamination migrating toward the property. Whole-house granular activated carbon filtration can address some VOCs, but the underlying contamination source matters. This warrants serious conversation with your real estate attorney and possibly the state environmental agency before proceeding.
Negotiating Around Water Test Results
Water quality findings are negotiable items, the same way structural issues are. If bacteria tests fail, a reasonable request is that the seller fund professional shock chlorination and cover the cost of a retest before closing. Most sellers comply — it's typically a straightforward fix.
For contamination that requires permanent filtration equipment, you can request a price reduction to cover installation, or ask the seller to install the system prior to closing. If the well requires significant remediation or if contamination points to a larger environmental issue, walking away may be the right call.
What's not reasonable: skipping the retest after treatment and just assuming the problem is resolved. Always get written documentation of the treatment performed and a lab-confirmed passing result before you sign off on the well water as acceptable.