Malibu Building About Percolation Test

Building in Malibu and getting a percolation test for a septic system

A percolation test consists of digging one or more holes in the soil of the proposed leach field to a specified depth, presoaking the holes by maintaining a high water level in the holes, then running the test by filling the holes to a specific level and timing the drop of the water level as the water percolates into the surrounding soil.

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

For leach line testing (the most common type throughout most of the country), a minimum of three test holes are drilled, most commonly six to eight inches in diameter. Ideally, these should be drilled to different depths from three to six feet below the surface. For better, more conclusive results, five drill holes are used in a pattern of one hole at each corner of the proposed leach field and one test hole in the center. Testing of these holes will result in a value with units of minutes per inch. This value is then correlated to a predetermined county health code to establish the exact size of the 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.

Please refer to Wikipedia for more information and call a local geologist. The city of Malibu building department is a newly designed office, and you can find further list of referrals.

You can also contact us and we will be happy to help you find land, structure a purchase agreement for you and guide you along the way.