Buying a House With a Well: The Complete Due-Diligence Checklist

A private well means no water bill — and no water company. The seller hands you an invisible underground system, and everything you don't verify before closing becomes your problem after it. This is the complete due-diligence list: the documents to demand, the tests to run, the numbers that matter, and the findings that should change your offer. (Buying a home with septic too? Run the septic inspection playbook in parallel — same clock, same contingency.)

Step 1: Collect the paper

• The well log (driller's report): depth, casing, yield at completion, geology. Public record in most states — if the seller doesn't have it, the state database likely does. No log at all = an undocumented well, priced accordingly.
• Water test history: a seller with annual results is telling you the well was managed; a seller with none is telling you something too.
• Equipment records: pump age and installer, pressure tank age, any treatment equipment and its service history (what that equipment should have cost — and what its presence hints about the water).
• Permits for well work — deepening, hydrofracking, pump replacements.

Step 2: Test the water — beyond the lender minimum

Some lenders and many states require a bacteria and nitrate test; FHA asks for one when local rules require it or the appraiser flags the well. Buy the full picture: the standard panel plus arsenic, lead, iron/manganese, hardness, and pH — with local additions (PFAS, radon, VOCs) where risk maps suggest. Our testing guide covers labs and sampling; for a purchase, have the inspector or lab collect the sample rather than the seller. Trust arrives by courier, not by promise.

Step 3: Measure — don't accept — the numbers

• Flow rate: a measured drawdown test (1–2 hours, $150–$400): 5+ GPM is comfortable, 3–5 GPM workable, under 3 GPM an engineering project. Check the result against your household with the usage calculator.
• Recovery: how fast the well refills after sustained draw — the difference between a well that handles guests and one that quits mid-shower.
• Pressure system health: short-cycling during the test means pressure tank problems — cheap to fix, useful to negotiate.
• Pump age vs. lifespan: submersibles run 10–15 years; a 14-year-old pump is a $1,500–$4,000 line item on your 5-year budget, not a today-problem — but your offer should know it.

Step 4: Walk the wellhead

• Casing rises 12+ inches above grade, cap sealed and intact, ground sloping away — the basics that keep surface water out.
• Setbacks: the well sits legally distant from the septic system (50–100 ft in most states — your state's rules), livestock areas, and fuel storage. On small lots, measure; don't eyeball.
• Location practicality: can a service rig reach it? A well under a new deck is a future demolition quote.

Red flags that change the offer

1. Bacteria or nitrate exceedance: often fixable (shock chlorination, treatment) — but the cause matters more than the hit. Nearby septic failure is a bigger conversation than a loose cap.
2. Flow under 3 GPM: price in storage ($2,000–$5,000) or accept scheduled living.
3. Undocumented or shared well: shared wells need a recorded agreement covering maintenance, costs, and easements — no agreement, no closing. Undocumented wells may not meet current code when work is eventually needed.
4. Treatment equipment with no explanation: a UV unit and three filters is either diligence or a confession — the water test history tells you which.
5. Sudden recent "improvements": a pump replaced the month of listing deserves the same skepticism as a freshly pumped septic tank.