Clear, accurate real estate definitions 1,443 terms 6 topics Free A–Z glossary
Buying & Selling

Percolation Test

Definition and meaning of Percolation Test in real estate.

A percolation test is a soil evaluation method used to determine the rate at which water is absorbed by the ground, helping to decide if the land can support a septic system.

In more detail

Commonly referred to as a perc test, this assessment is crucial when buying undeveloped land that does not have access to a municipal sewer system. A licensed engineer or sanitarian digs test holes on the property, fills them with water, and measures how quickly the water level drops.

The absorption rate determines the size and type of septic drain field required, which is the underground area of soil where wastewater is filtered. If the soil does not drain well, the land may be deemed unsuitable for building a home.

Key facts

CategoryBuying & Selling
Also Known AsPerc test
Required ForOn-site septic system design
Test Performed ByLicensed sanitarian or civil engineer
Example

Before finalizing the purchase of a rural lot, the buyer hired a technician to perform a percolation test, confirming the soil drained fast enough to support a septic system.

Frequently asked questions

What happens if a property fails a percolation test?

If land fails a perc test, it means the soil does not drain well enough for a traditional septic system. You may not be allowed to build on the property unless you install an expensive alternative septic system, such as a mound system.

How long is a percolation test valid?

The validity of a perc test varies by county and state guidelines, often ranging from two to five years, though some jurisdictions allow them to stand indefinitely if the soil conditions or zoning regulations have not changed.

Related terms