Human contact with sewage is a serious public health risk. Drinking water
contaminated with sewage can cause health problems such as diarrhea, nausea,
cramps, dysentery and hepatitis. Exposure to sewer gases can also cause
discomfort and illness. For at-risk areas, connecting to an adequate public
sewer system is generally the best alternative for disposing of domestic
sewage from private residences. Where access to a public sewer system
is unfeasible or too expensive, proper sitting and design of an onsite
sewage system is critical to avoid its premature failure.
||A septic tank system consists of three major components: the septic tank, a distribution device and an absorption field.
septic tank system consists of three major components: the septic tank,
a distribution device and an absorption field. A septic tank is a large,
watertight, corrosion-resistant, buried container that receives raw sewage
from the plumbing drains of the home. In it, solids are separated out
of the raw sewage and are partially digested by anaerobic (oxygen-lacking)
bacteria. The septic tank must be large enough to allow retention of the
raw sewage and some decomposition for at least 48 hours. Solids that are
not digested either float to the top to form a scum layer or settle to
the bottom of the tank as sludge. Depending on tank size and sewage volume,
the sludge and scum must be pumped out at least every 2 to 5 years to
allow bacterial digestion to continue in the tank.
Otherwise, raw sewage may flow directly through the tank and into the
absorption field, causing its failure. After primary treatment in the
septic tank, the liquid effluent flows through the distribution device,
which ensures that equal quantities of effluent go to each pipe in the
absorption field. The absorption field is a subsurface leaching area within
the soil that receives the liquid effluent from the distribution device
and distributes it over a specified area where it is allowed to seep into
the soil. The filtering action of the soil, combined with further bacterial
action, removes disease organisms and treats the harmful material in the
effluent, completing the treatment process so that the water is recycled
to the surface or groundwater source.
many situations, an existing system that is failing may not be "repairable."
Thus a completely new system may be needed. Misuse of individual sewage
systems results not only in water quality problems and nuisance conditions,
but also in costly repairs to rehabilitate a failing system. Failing systems
include both those that you can see and smell and those that seep effluent,
or waste liquids, into groundwater supplies before the soil can properly
remove disease-causing pathogens.
considering options for selecting the location for a new water well, contractors
and property owners should also consider the likelihood of having to replace
the on site waste disposal system in the future, and where that system
would have to be located. This area should then be eliminated from consideration
as a possible site for the well. Planning for the future in this way could
prevent major headaches and expense down the road.
standards for wells and septic tank systems vary widely from state to
state, but most range from 50 to 100 feet. Setback distances may increase
when special limiting factors exist, such as the presence of limestone,
karst or fractured bedrock in the soil formation. Contact your local health
department for the particular setback regulations in your community and