Most buyers give the roof, the foundation, and the furnace their full attention, then skim the water paperwork tucked into the sale packet. That sheet deserves a slower read. A single line can say a contaminant was not found, and that line means less than it sounds like it does.
What Not Detected Actually Says
Labs report results against a reporting limit, the lowest level a given method can measure with confidence. When a sample comes back below that limit, the report usually shows a phrase such as not detected. That is not the same as a measured zero. It means the lab could not confirm an amount at its level of measurement. Lab methods differ, too, so two labs can report different limits for the same compound.
The same gap sits at the center of current reporting. On October 23, 2026, Circle of Blue published a piece, originally from Inside Climate News, under the headline "PFAS Contamination in Drinking Water May Be Underestimated." The headline points to the concern that matters for buyers: when levels sit below what labs can report, the picture on paper may be incomplete. You can read the full report on Circle of Blue's coverage of PFAS in drinking water.
Five Questions Before You Accept a Clean Line
First, ask for the reporting limit in writing. The number usually sits beside the result. If it is high relative to the standards your state or local health department uses, the test may not be able to answer the question you care about.
Second, ask where the sample was taken. A kitchen tap run for a set time is the usual household approach. An outdoor spigot, a storage tank, or a point before treatment tells you something different, and the report should say which one it is.
Third, ask who ordered the test and when. A result the seller commissioned is useful context, but it is not a substitute for your own sample. Buyers can usually request a water test during the inspection period, which is the window to do it.
Fourth, if the home is on public water, read the utility's annual water quality report. It shows what the utility tests for at the treatment plant and in its distribution system. That is valuable, though it may not match the faucet in your kitchen, especially in an older house with its own plumbing.
Fifth, if the home is on a private well, confirm whether PFAS was tested at all. Common well panels often cover bacteria, nitrate, and some metals. PFAS usually needs a separate request to a lab, so a clean well sheet can simply mean that test was never run.
What to Do With the Answers
If your own sample shows PFAS above the standard your local health department uses, the next step is a conversation with that department and a qualified water treatment professional. Treat it as a decision to make with them, not a guess drawn from a single number. If the result is non-detect with a documented low reporting limit, you have a useful baseline. Keep that report with your closing papers so future tests can be compared against it.
The inspection window also gives you leverage. If the packet's water sheet is thin, ask the seller to supply the missing details, or use the test result to request a repair credit or a price change. Do it before the contingency period closes, not after.
A clean line in a sale packet is a starting point, not the end of the question. Read the limit, the sample location, and who ran the test, then decide how much weight it deserves against your own result.