A perc test (or perk test) is short for a percolation test. This is a test which measures the soil’s ability to absorb water; this will determine if a septic system will function on the site.
The traditional method of perc testing is to dig three holes in the area where the septic disposal drain field is to be located. These holes will be 6 to 8 inches in diameter and 2-3 feet deep. The holes would then be filled to the top with water. After the water has been absorbed into the ground, the perc test begins.
Water is then poured -again- into the holes to a depth of 10 inches from the bottom of the hole. A board is laid across the top of the hole and the distance from the bottom of the board to the top of the water is measured. Make note of this distance and the time.
Do not add any water during the test. After one hour, measure the distance from the board to the top of the water again. The difference between the first measurement and the second is the inches-per-hour absorption rate. Continue the test by recording the distance down to the water level for five consecutive hours, or until all the water has been absorbed. If the water is absorbed before the end of the five hour test period, the perc test is over.
Generally speaking, if the last hourly rate of absorption is less than 1 inch in 60 minutes, then a septic system drain field will probably not work in that area. Areas where clay or hardpan type soils are near ground level are not satisfactory for disposal fields.
Roughly speaking if the dig sites are rich in gravel or sandy soil, it will likely perc. If the soil has a lot of clay or if the water table is too high it probably won’t perc.
Can you build on a site that does not pass a perc test?
Yes. One of the most common misconceptions about vacant land is that if it doesn’t perc it’s the end of the world. Contact SES for options.
Call SES today at 1-866-249-5630 and leave your Perc Testing worries in Great Falls, VA to us.
Do you have property with one or more of the following limitations or needs? No problem for SES!
- Limited Area
- Steep slopes
- Shallow, rocky, clayey, wet or sandy soils
- High groundwater
- Sites where the current system has failed
- Coastal Areas where nutrient removal is required
- Commercial Properties like Restaurants & Schools
- Subdivision and Communal Systems