The 2 most common reasons to get a Hydraulic Load Test are:
If the home has been vacant for more than 7 days it is highly recommended that a Hydraulic
Load Test be performed because it simulates average usage, as if the home were occupied.
Without a Hydraulic Load Test a Septic Inspection on a vacant home would be incomplete
because it would be impossible to verify if the absorption area could properly drain the daily
usage of liquid.
A Hydraulic Load Test is recommended for an occupied home if there is going to be a
significant increase in the amount of people living in the home. It would verify if the absorption
area could properly drain the increased usage. Doing a Hydraulic Load Test on an occupied
home requires the Inspector be specially trained and diligently take the proper precautions so
the absorption area is not overtaxed and the Hydraulic Load Test does not misrepresent the
actual condition of the absorption area. If the right conditions are not present then it may not be
possible to do a Hydraulic Load Test on an occupied home.
What to expect during a Hydraulic Load Test
First the amount of liquid in the absorption area is measured, then a predetermined amount of
water is introduced into the system. The amount of water introduced is formulated using the
Pennsylvania DEP's (Department of Environmental Protection) estimated peak flow per number
of bedrooms in the home. While the water is being added the level of liquid in the absorption
area is being monitored, when the complete amount of water is in the system the liquid level in
absorption area is measured again. These steps are repeated after waiting 24 hours. The
second day's measurements are compared to the previous days measurements to determine if
the absorption area is functioning properly and can drain the estimated daily usage of liquid.