When liquids within the tank rise to the level of the outflow pipe, they enter the next part of the treatment system (pre-treatment device, distribution box, pump chamber, etc, depending on the type of system). Bacteria, which are naturally present in all septic systems, begin to digest the solids that have settled to the bottom of the tank, transforming a large percentage of these solids into liquids and gases. The biologic process begins in the tank where the effluent separates into layers and begins the process of decomposition. Most tanks are split into two compartments and have pipe baffles and an outlet filter to ensure the solids stay in the tank. The first component of all septic systems is the tank. The septic system is a natural method of treating and disposing liquid household waste. The rules are not perfect, but most have been created based on documented problems and some scientific research. Today’s regulators have studied many of these problems previously experienced and changed the septic system regulations to help increase the life of our systems and also try to protect the public from contamination of surface and ground water. This caused contamination of our ground water which was also found to be a problem.

On sites with excessively well drained soils (fractured rock, etc), there wasn’t enough filter material (dirt) to adequately treat the effluent before the pollutants made it into the aquifer. Having a drainfield in a “perched” water table would oftentimes cause the system to back up into the house or cause pre-mature failure. Sites with poor draining soils were found to sometimes have a seasonal water table near the surface in the wintertime. Putting the liquid waste into the ground instead of straight into our surface water was a good first step, but other problems ensued. This type of a system allowed the solids to settle out in a tank and the liquids to be filtered by gravity through the native soil. To help solve these initial problems, “standard gravity” soil treatment systems were introduced. After discovering this method of wastewater disposal pollutes our waterways, causes disease and can be lethal to humans and animals, newer methods were created. Back in the “old days”, the standard method of liquid waste disposal was to install a pipe from the house to the closest water body and let it all go downhill.

Septic tank modern design