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The Impact of Septic Systems on the Environment

Nearly half of the homes and businesses in the Long Island Sound watershed have septic tank waste disposal systems. When properly sited and maintained on a routine basis, septic systems are an excellent waste management alternative. However, when not properly sited or maintained, they can cause contamination of surface and groundwater resources, which leads to public health and pollution problems.

How Septic Systems Work

Septic systems have two key components, a receiving tank and a leaching system. A sewage line carries wastewater from the kitchen, bathroom and laundry room to the underground septic tank, where heavy particles settle out of the liquid, forming a layer of sludge on the bottom of the tank. Light materials float, forming a layer of scum on top of the water in the tank (see Figure 1). Bacteria use the solid materials, liquefying these waste products. To allow sufficient time for particles to settle and for bacteria to break down the sludge, a septic tank should be large enough to hold at least one day’s flow of wastewater from the home, and to provide storage for sludge and scum.

To view the full septic system fact sheet, download the pdf document

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