A septic tank is primarily a holding tank, made of fiberglass, plastic or concrete, designed to hold the amount of waste a house hold will produce in a 24 hour period. The waste generally comes from the kitchen sink, washing machine, and bathrooms. The Department of Health will approve separate systems for washing machine lines when requested by homeowners. These are commonly referred to as Gray water tanks. This is designed to avoid large surges going into the septic system and harsh washing machine powders and bleach that may adversely affect the bacteria break down action in the septic tank.
The material flowing into the septic tank is divided into three general categories:
*Sludge– heavy solids that sink to the bottom of the tank
*Grease/scum– floats near the top of the tank
*Water– Fills the tank
The solid waste is decomposed by bacteria and the liquids ordinarily flow by gravity into the drain field. If, under normal gravity conditions, it is impossible to reach the distance of the drain field, pumps can be installed to raise and push the liquid into an elevated drain field system. The solids are prevented from going into the drain field by an outlet filter or baffle on the outlet end of the septic tank. If the tank is not pumped regularly to remove the solids accumulated at the bottom, the tank will fill with sludge and the solids could be washed out into the drain field. If the solids reach the drain field, it will clog the soil and eventually lead to system failure.
Another concern for a septic system is whether the septic tank or holding tanks are structurally sound and in good condition. Evaluation of the tank for structural soundness starts as soon as the lid is removed. If the lid and tank are concrete the bottom of the lid should be evaluated. If the concrete shows signs of deterioration and spalling, this could be a sign that the integrity of the tank is compromised. For a plastic or fiberglass tank, if the lid or access hole is miss-proportioned it is an indicator that the tank has been structurally deformed.
The top of a concrete tank should be evaluated for corrosion and cracks. If the lid and top are corroded and if there is any rebar showing, the tank top and lid should be replaced. The rest of the tank’s appearance will determine whether the entire structure needs to be replaced or only the lid(s).
*All specifications of pour conditions are referred to and enforced by Florida Administrative Cod 64E-6.