Perc test

A test that measures how fast water drains through the soil, to see whether the land can support a septic system. Standard step before building in rural areas without sewer.

Also called percolation test · Inspections & appraisals · Updated September 2026

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Part 1 of 4

Why a seller cares

A perc test says whether land can take a septic system, and a buyer of a lot or a rural home without one may ask for it. A home with a working septic usually does not need one; a vacant lot almost always does.

Part 2 of 4

A simple example

You are selling five acres with no sewer. The buyer's offer is contingent on a perc test, done by the county health department.

Perc test: a simple example
What the test findsWhat follows
The soil drains at an acceptable rateA septic permit is possible; the sale proceeds
The soil drains too slowlyA different system, an engineered one, or a buyer who walks
The home already has a working septicA perc test is rarely asked for; a septic inspection is

A perc test is about what can be built. A septic inspection is about what already is.

Part 3 of 4

What people get wrong

That a failed perc test means the land is worthless. It means a standard septic will not work there, and there are other kinds.

Part 4 of 4 · where to read next

Where it appears in the sale

What a definition is, and what it isn't

Keighbor is a software company, not a law firm, brokerage, or tax adviser. This is general information, not legal, tax, financial, or real estate advice about your sale. Your situation may differ. Before acting on a contract, disclosure, title, tax, or pricing question, ask an appropriately licensed professional in your state.

Written and researched by Keighbor Research · drawn from the reference glossary · how we research and check what we publish

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