By: Gene Rodriguez, III
As a homeowner, you may have wondered about the types of septic systems available. The site and soil conditions typically determine what types of septic systems are possible on a given property. Beyond site limitations, cost and service requirements are also important considerations.
Types Of Septic Systems In Use Today
- Gravity/Conventional - Gravity septic systems use the downward flow of water to carry wastewater from the house to a septic tank and then down and out to a drain field where waster water is filtered by the surrounding soil. The septic tank is a large, single or multi-chambered tank buried under ground. The purpose of the septic tank is to filter out solids from wastewater before it enters the drain field. The drain field is series of connected pipes that slowly seep wastewater into the soil where natural filtering and bacterial action remove and breakdown harmful materials from the water.
- Pressure Distribution - In low or flat terrain, pressurized distribution septic systems employ an electrically driven pump to move water out of the septic tank and into the drain field. These pumps may be operated by a timer or float system that determines when to pump excess wastewater through the system. Pressure distribution is an effective way to move wastewater evenly over the drain field.
- Sand Filter - Sand filtered septic systems are designed similarly to gravity systems, except that they add a pump and sand filter unit. The pump moves waster water from the septic tank into the sand filter. The sand filter is waterproof chamber filled with a sand-filtering medium. As the wastewater passes through the sand filter, waste material is removed before the water passes on the drain field. Sand filter are typically used in areas where the surrounding soil is thin or the water table too high to allow a drain field to function properly by itself.
- Mound - Mound type septic systems function similarly to sand filter systems, except an above ground, sand-filled mound replaces the sand filter and drain field. A pump system is used to move wastewater to the top of the mound, where it is gravity filtered through the sand before entering the soil below. Mound type septic systems are typically used in coastal areas or wherever there is insufficient soil for drain field distribution and filtering.
- Aerobic - Aerobic septic systems use modified septic tanks that supply oxygen to aerobic bacteria in the tank. The bacteria greatly increase the rate at which solid wastes are broken down. Aerobic systems produce effluent of very high quality, but require ongoing maintenance and certification by local health officials.
