What Is a Perc Test?

If you're buying land, no whether you plan to build your dream home from scratch or place a manufactured or modular home on it, you'll probably need a septic system (unless you're buying a city lot that can easily be hooked up to the sewer).  A perc test (short for percolation test) is something that's required to design a septic system. 

Here's a good explanation from Wikipedia:

"A percolation test (from percolation, colloquially called a perc test) is a test to determine the absorption rate of soil for a septic drain field or "leach field". The results of a percolation test are required to properly design a septic system. In its broadest terms, percolation testing is simply observing how quickly a known volume of water dissipates into the subsoil of a drilled hole of known surface area. While every jurisdiction will have its own laws regarding the exact calculations for the length of line, depth of pit, etc., the testing procedures are the same.

In general, sandy soil will absorb more water than soil with a high concentration of clay or where the water table is close to the surface."

Here's a how-to on running a perc test.

Many times, when you're buying land from another owner, a perc test may have already been done.  Make sure to ask as this means you can avoid an additional cost.