Understand Your Septic System

Understand Your Septic System

A septic system, properly installed, operated and maintained properly is critical to the system’s ability of protect human health and the environment, especially drinking water and water quality. A septic system, improperly maintained, can contaminate your drinking water, as well as allow high amounts of phosphorus to run into our lakes and rivers. Knowing how a septic system works is the first step in operating and maintaining a proper system.

In most on-site treatment systems, wastewater is co-mingled, treated, and dispersed by one system, commonly made up of plumbing, septic tank and a soil treatment area. The plumbing collects water from all the various fixtures and appliances and delivers it to the septic tank, an underground watertight container where the real work of getting household wastes ready for distribution into the soil treatment area occurs.

In the septic tank, incoming and outgoing baffles trap the solids, which are then separated from the liquids and stored until they decompose or are removed. The light solids float to the top of the tank, forming a scum layer, and the heavy solids sink to the bottom, forming a sludge layer. The organic solids, such as food and human waste, are decomposed by naturally occurring bacteria that partially liquefy the solid material. The liquid is carried out to the soil treatment area – the drain field – and the undigested materials remain in the tank as sludge.

The tank also contains inspection pipes to allow for monitoring and a manhole through which the accumulated solids in the tank are pumped out at a recommended schedule of every one to three years, depending upon the amount of use to the system. The size of the tank depends on the number of fixtures and the potential water use. Pumps and lift stations deliver the wastewater to the septic tank and from the tank to the drain field if gravity flow is not adequate.

Every time raw sewage enters the septic tank, an equal amount of the partially treated liquid, called effluent, is forced out of the tank to the drain field, which is a network of pipes surrounded by small rock and soil. The effluent contains small amounts of suspended and dissolved matter, including disease-causing organisms and nutrients. These liquids leach out through holes in the drainage field pipes. A biomat of material is formed and restricts the flow of liquids to keep the soil beneath it unsaturated. Naturally occurring bacteria further treats the effluent and destroys the disease-causing organisms. Nutrients, such as phosphorus, are attached to the soil particles they come in contact with.