Septic Tank Systems

A Usage Guide

THE HOUSEHOLD PLUMBING AND WASTE SYSTEM

If you are like most people, you know very little about your septic tank system.  This is understandable.  In urban and suburban areas there are sewers to carry household waste to municipal wastewater treatment facilities.  In more rural areas, however, septic tank systems provide the functions of both sewers and treatment facilities.

All household waste is disposed of through the septic systems.  The proper operation of the septic system is essential to public and private health, to property values, and to the environment.  To see if you know enough about your septic system, answer the following questions.  If you cannot answer all the questions, your septic system could become a huge aggravation, public nuisance, health hazard and financial burden.

• Do you know what a septic tank is and how it works?
• Do you know what kind of soil absorption area you have and how it works?
• Do you know what causes septic systems to fail?
• Do you know what it costs to replace a failed septic system?
• Do you know how to keep a septic system from failing?
• Do you know that failed and failing septic systems contribute to pollution?

These are very serious questions.  The health of your family and the value of your property rely heavily upon the answers to these questions.

'An ounce of prevention is worth a pound of cure" was never more true than it is with septic tank care.  A small commitment to the care of your septic system will protect you indefinitely from the nightmare created by a failing system.  This pamphlet will attempt to give you a clean picture of how household waste is treated from drain line to soil.

The quantity and composition of waste generated in the home varies according to the number of residents, their personal water usage, and the water-utilizing appliances in the home.

 THE SEPTIC TANK SYSTEM

The Septic tank system is a small, on-site sewage treatment and disposal system buried in the ground.  The septic system has two essential parts: (1) the septic tank and (2) the soil absorption area.

The Septic Tank

The Septic tank was patented in London around 1900.  Webster's Dictionarydefines the septic tank as "a tank in which waste matter is decomposed through bacterial action."  The modern septic tank is a watertight box usually made of precast conrete, concrete blocks, or reinforced fiberglass.  When household waste enters the septic tank several things occur:

1. Organic solid material floaats to the surface and forms a layer of what is commonly called "scum".  Bacteria in the septic tank biologically convert this material to liquid.
2.  Inorganic or inert solid materials and the by-products of bacterial digestion sink to the bottom of the tank and form a layer commonly known as "sludge".
3. Only clear water should exist between the scum and sludge layers.  It is this clear water - and only this clear water - that should overflow into the soil absorption area.

Solid material overflowing into the soil absorption area should be avoided at all costs.  It is this solids overflow that clogs soil pores and causes systems to fail.  Two main factors cause solid material to build up enough to overflow: (1) bacterial deficiency, and 92) lack of sludge removal.

Bacteria MUST BE PRESENT in the septic tank to break down and digest the organic solids.  Normal household waste provides enough bacteria to digest the solids UNLESS any harm is done to the bacteria.  Bacteria are very sensitive to environmental changes.  Check the labels of products you normally use in the home.  Products carrying harsh warnings such as "HARMFUL OR FATAL IF SWALLOWED" will harm bacteria.

The following commonly-used home care products - even when used according to directions - can reduce the bacteria population required for proper septic tank operation.

  • detergents                  • bleaches                • cleaning compounds
  • disinfectants                • acids                     • sink & tub cleaners
  • toilet cleaners              • polishes                 • caustic drain openers

People rarely think of the effect of these products on the septic tank system when the products go down the drain.  What kind of effect do you think anit-septics have on your septic tank?

Bacteria must be present to digest the scum.  If not digested, the scum will accumulate until it overflows, clogging the soil absorption area.

The sludge in the septic tank - inorganic and inert material - is not biodegradable and will not decompose.  If not removed, the sludge will accumulate until it eventually overflows, again clogging the soil absorption area.

SOIL ABSORPTION - OR LEACHING - AREA:

There are many, many soil absorption or leaching systems - too many to discuss them all.  There are, however, two general types of facilities to carry off the overflow water from the septic tank:  (1) trench systems and (2) drainage pits.

Trench systems - also called leaching fields, drain fields, or finger systems - generally consist of a network of perforated pipes laid in a gravel-lined trench.  Solids clogging pipe perforations, gravel lining, or the soil pores outside the trench will cause drainage to slow eventually stop.

Drainage pits - also called drywells or cesspools - are made of precast concrete block.  They are cylinders with closed tops, open bottoms, and holes in the sidewalls.  Some older systems consist of only a drainage pit or cesspool.

Solids accumulating on the interior surfaces of the pit or in the soil will again contribute to sluggish drainage or failure.