The Septic System

A septic system is a wastewater treatment and disposal system. Its purpose is to separate household wastewater into a solid and liquid phase, and perform a certain amount of treatment and purification of those wastes prior to their disposal. The typical septic system consists of two main parts: the septic tank and the absorption field.

The septic tank: Upon leaving the house, wastewater first enters the septic tank. The purpose of the septic tank is to separate the solids from the liquids, using a series of baffles. The solids, in the form of sludge which collects on the bottom of the tank, and scum, which floats on the top of the water, remain in the tank and must be pumped out regularly. Sewage effluent (the liquid phase) exiting the septic tank is a cloudy liquid that still contains many pathogens (disease causing organisms) and other pollutants, such as phosphorus.

The absorption field: Liquid wastes leave the septic tank and pass on to the absorption field (sometimes called a leach field). Typically, an absorption field consists of perforated pipes buried in gravel-filled trenches. Sewage effluent passes through the holes in the pipe, trickles through the gravel, and is absorbed by the soil. As the effluent flows through the soil, many of the pathogens are filtered out by the soil particles. Under ideal conditions, the soil retains some of the nutrients, including most of the phosphorus and some forms of nitrogen.

Outhouses: An outhouse is a hole in the ground with several above ground improvements added to accommodate modesty and comfort. Since few liquids are introduced into an outhouse, an outhouse is less likely to pollute nearby lakes and streams. A properly sited outhouse should be well away from the water. The bottom of the waste pit should be a minimum of two to three feet above the seasonal high groundwater level. Care should be taken to divert surface water runoff away from the waste pit.

Septic System Testing

Inspection: A septic system requires regular maintenance to function properly. Most importantly, the level of sludge and scum must be inspected and measured every three to five years under light use. The purpose of a septic system inspection, therefore, is to determine if pumping is necessary (see Maintaining your Septic System for more details).

The Dye Test: The purpose of a dye test is to locate obvious, catastrophic failure of a septic system. During a dye test, a measured amount of fluorescent dye is flushed into the system. This is followed by an inspection of nearby waters for appearance of the dye over a period of 1 to 2 hours. A dye test will only measure septic system failure if there is a broken pipe, a direct pipe into the lake or stream, or some other direct way for the septic effluent to pass directly into nearby surface waters. It is likely that old and/or improperly functioning septic systems still pollute nearby waters even though they have passed a dye test.

Maintaining your Septic System
 

Septic tank pumping: A septic system requires regular maintenance to function properly. The tank must be cleaned out regularly so that sludge and scum do not build up. If the tank is not cleaned regularly, sludge and scum will clog the outlet pipe or absorption field, which will lead to a failure of the absorption field and the spread of pathogens and nutrients into nearby lakes and streams. Septic tanks must be pumped if the total thickness of sludge plus the scum is more than one third the total liquid level in the tank (typically a sludge level of six to eight inches) or if the scum is more than 4 inches thick.
 

Good Practices: The following are some good practices (Dos and Don'ts) that, if followed, will minimize maintenance costs, prolong the life of your system, and most importantly protect your lake and groundwater.
 
 

• Limit the water entering your septic tank. Use water saving fixtures; fix toilet float valves, leaks, and dripping faucets; spread clothes washing over the entire week.

 
• Pump the tank when necessary. This means every two or three years (more often if you use a garbage disposal, less often if the system only receives seasonal use) or as indicated by your inspection.

 
• Divert surface water drainage away from the absorption field.

 
• Use alternatives to caustic drain openers and toxic cleaning compounds. Unclog drains with boiling water or a drain snake. Clean toilets, sinks, showers and tubs with mild detergent or baking soda rather than stronger commercial bathroom cleaners.

• Do not connect a sump pump or other "clean" water discharges to the septic tank.

 
• Do not put materials down drains that will clog the septic tank (fats, grease, coffee grounds, paper towels, sanitary napkins, disposable diapers, diaper wipes, etc.).

• Do not put toxic substances in drains (cleaning fluids, oils, paints, disinfectants, pesticides, etc.).

 
• Do not use chemicals to clean or "sweeten" your septic system. They may interfere with the natural biological action in the tank, clog the drain field by flushing sludge and scum into the field, or add toxic chemicals to groundwater. Septic tank "starters" and "enhancers" are not necessary for existing, new or newly pumped out tanks.

F. X. Browne, Inc., 800-220-2022, info@fxbrowne.com

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