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  • Individual Sewage Disposal System Operations and Maintenance


    The typical ISDS consists of a septic tank and absorption bed (sometimes called the leaching field). The septic tank is usually made of concrete or other durable materials. Most tanks will have a capacity of 1,000 gallons or more and will be divided into two compartments. Sewage (or effluent) from the dwelling flows through a building sewer and enters the first compartment of the tank. Here, bacterial decomposition occurs and materials which cannot be digested settle to the bottom as sludge or float to the top to form a scum layer.

    The remaining liquid then flows into the second compartment of the tank through a series of baffles, where additional treatment occurs. Although most tanks are non-mechanical, some will have a motor or aerator which agitates the sewage. These mechanisms are an integral part of the tank and should not be removed or disconnected as this may seriously affect the operation of the system.

    From the tank, the effluent is piped to the absorption bed and enters a series of perforated pipes bedded in gravel and underlying soil before flowing naturally back into the groundwater system. The filtering action of the soil removes most of the harmful bacteria. The result is a high degree of treatment occurring in a natural, environmentally sound process.

    Not all contaminants can be removed by these systems. Nitrates, a chemical by-product of human waste, are not removed and may impact the groundwater. Distance separation from wells and proper system maintenance is necessary to increase treatment effectiveness as well as the life span of the system.


    Last Updated: 4-24-2013