IAPMO Certified Septic System Tanks
The Purpose of a Septic System
- To provide time and space for heavy solids or light greases to separate out of the sewage,
- To provide a place for anaerobic (non air breathing) bacteria to break down the sewage, providing up to 60% reduction of undesirable solids and contaminants, and
- To provide for flow of effluent (discharge liquid) from the cleanest portion of the tank by means of baffles of outlet tees.
Components of a Typical Private Septic System
SEPTIC TANK: A watertight container with a usual capacity in excess of 750 gallons, plus air and scum space equivalent to approximately 25% of water capacity. The tank should be baffled or (preferably) compartmentalized to prevent direct flow-through, and each compartment should have a riser to grade for cleaning. The tank should be made of durable material and strong enough to withstand earth and pedestrian loading. Selvage Concrete tanks and lids are reinforced with 3/8” steel rebar 6” on center with 5” of concrete, and are built to accept 24” risers to facilitate inspection and thorough cleaning.
DIVERSION VALVE: A small box with one inlet and two outlets, with a diversion valve to alternate the outlet flow. This component is used with split dispersal fields to direct flow to one or the other field.
DISTRIBUTION BOX: A small concrete box with one inlet and multiple outlets to disperse the flow of the effluent to several lines of a dispersal field. Some locations may not require distribution boxes.
DISPERSAL FIELD (Also called a Leach Bed or Leach Field): An underground system of trenches filled with stone or gravel, covered to reduce surface water inflow and containing perforated pipes to disperse the effluent and provide for passage into the soil where aerobic (air breathing) bacteria can destroy undesirable elements. Usually expressed in lineal feet of 12” to 36”, the field is made up of wide trenches approximately 2 feet in depth.
FILTER BED/MOUND SYSTEM: A bed with a perforated pipe embedded in course stone, on top of which are layers of graded filter sand. The effluent is dispersed over the top of the bed by means of the perforated pipe, and aerobic bacteria live in the bed to clean the effluent. The bed may either be underground (subsurface) or above the ground (surface), and may or may not be confined by concrete walls or a container. Usually expressed in square feet of surface areas, a 10’ x 20’ filter bed would be 200 square feet.
HOLDING TANKS: A holding tank is not a septic system. Holding tanks are used when an on-site wastewater disposal system cannot be installed on the property due to shallow bedrock, shallow groundwater, etc. A holding tank stores all household waste and must be pumped when full. Waste is taken to an approved disposal field or municipal treatment plant.
LIFT STATION (also called Dosing Station): A container for the collection of effluent, a pump or siphon is used to raise or disperse fluid to a dispersal field, filter bed or point of discharge. Lift stations are used where flooding of the field or filter is desirable, or where elevations will not permit gravity flow.
Septic System Components in Santa Rosa
Septic Tank Sales in Santa Rosa, Petaluma, Vallejo, Napa, Novato,
Rohnert Park, Fairfield & San Rafael