There are two primary groups of In-ground Gravity Private Onsite Wastewater Treatment Systems (POWTS). One group is a POWTS using washed stone to support and raise the perforated piping network within the POWTS cell. The second type of inground gravity POWTS is a stone-free system.
Most often the pressurized POWTS you will hear about will be one of the following: a mound, an at-grade, or an in-ground pressurized system.
Holding Tanks are typically installed on sites that may not have sufficient suitable soils or area on the lot for any other type of Private Onsite Wastewater Treatment Systems (POWTS) to be installed.
The primary purpose of a Pretreatment System, simplistically stated, is to reduce the high levels of organic matter contained in wastewater. Private Onsite Wastewater Treatment Systems (POWTS) having a pretreatment unit are those POWTS that will have some type of pretreatment unit added to the standard POWTS components.
Pretreatment units can be placed in one of two categories, namely: suspended growth and fixed film processes.