When a well water test fails during a real estate transaction, it can delay or stop closing altogether. Buyers, sellers, and lenders often assume a failed result means the well itself is contaminated—but that is not always the case.
Common Reasons Well Water Tests Fail
Most failed well water tests fall into three categories:
1. Lead
Elevated lead results are most commonly associated with interior plumbing materials, stagnation, water chemistry, or sampling conditions—not the groundwater source itself. Lead is rarely present in aquifers and is typically introduced after the well, within the building plumbing.
2. Nitrates and Nitrites
Nitrates and nitrites typically originate from surface influence and land use activities such as agriculture, septic systems, or rainfall infiltration. Shallow wells and poor well construction increase vulnerability.
3. Total Coliform or E. coli
Bacterial detections indicate a sanitary integrity concern. These results are commonly tied to wellhead protection, surface intrusion, drainage issues, or seasonal conditions.
What Lenders Care About
Lenders are not looking for explanations—they are looking for passing results. Until corrective action is taken and a certified passing retest is submitted, the water supply is considered unacceptable for loan approval.
Bottom Line
A failed well water test does not automatically mean the well is permanently unsafe. It means corrective action and retesting are required before closing can proceed.
