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Septic
Systems and Water Quality
Twenty-three percent of the U.S.
population relies on onsite wastewater treatment systems, most of which
are septic systems. A septic system is a highly efficient, self-contained,
underground wastewater treatment system which uses
natural processes to treat wastewater, usually in a homeowner’s
backyard. According to the EPA, properly
sited, constructed and managed onsite wastewater treatment systems are an
effective means of protecting human health and the environment. In They
also avoid potentially large transfers of water from one watershed to
another, that can occur with centralized collection and treatment.
However, inadequately functioning
and/or failing septic systems can contribute to the contamination of
groundwater, streams and other bodies of water. Wastewater from septic
systems may include many types of contaminants, such as nitrates, harmful
bacteria, and viruses. Various geologic conditions, such as fractured
bedrock and shallow groundwater tables, may allow pollutants, bacteria and
viruses to be transported very rapidly and can contaminate nearby drinking
water supplies.
How to
Maintain Your Septic System
If you own a septic system, it is
important that it be properly maintained to extend its life and prevent
contamination of ground and surface water. It is recommended that you have your
septic tank inspected and pumped out as needed every three to five years. How often you need to pump the
solids out of the septic tank depends on three major factors:
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The number of people in your
household;
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The amount of wastewater
generated (based on the number of people in the household and the
amount of water used);
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The volume of solids in the
wastewater (e.g., using a garbage disposal will increase the amount
of solids).
Although your septic tank absorption
field generally does not require maintenance, you should adhere to the
following rules to prolong its functional life:
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Do not drive
over the absorption field with cars, trucks or heavy equipment;
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Do not plant
trees or shrubbery in the absorption field, because the roots can get
into the lines and plug them;
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Do not cover
the absorption field with hard surfaces, such as concrete or asphalt.
Grass is the best cover, because it will help prevent erosion, and
help remove excess water.
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Do
divert surface runoff water from roofs, patios, driveways and other
areas away from the absorption field.
What NOT
to Send Down the Drain
Homeowners wanting to take good care of
their septic systems should make note of the following items that should
never be flushed down the drain or toilet. These items can overtax the
system, or clog the pumps and tiles:
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hair combings |
coffee grounds |
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disposable diapers |
condoms |
| dental floss |
sanitary napkins |
| kitty litter |
tampons |
| cigarette butts |
gauze bandages |
| paper towels |
fat, grease or oil |
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How
Does Your Septic System Work?
A septic system consists of two
main parts – a septic tank and a drainfield. The septic tank is
a watertight box, usually made of concrete or fiberglass, with an
inlet and outlet pipe. Wastewater flows from the home to the
septic tank through the sewer pipe. The septic tank treats the
wastewater naturally by holding it in the tank long enough for
solids and liquids to separate. The wastewater forms three layers
inside the tank. Solids lighter than water (such as greases and
oils) float to the top, forming a layer of scum. Solids heavier
than water settle at the bottom of the tank, forming a layer of
sludge. This leaves the middle layer of partially clarified
wastewater.
The layers of sludge and scum
remain in the septic tank, where bacteria found naturally in the
wastewater work to break the solids down. The sludge and scum that
cannot be broken down are retained in the tank until the tank is
pumped. The layer of clarified liquid flows from the septic tank
to the drainfield.
A standard drainfield (also
known as a leachfield, disposal field or a soil absorption system)
is a series of trenches or a bed lined with gravel or course sand,
and buried one to three feet below the ground surface. Perforated
pipes or drain tiles run through the trenches to distribute the
wastewater. The drainfield treats the wastewater by allowing it to
slowly trickle from the pipes out onto the gravel and down through
the soil. The gravel and soil act as biological filters.
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Septic Tank |
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The septic system
cleans waste water, which is further purified as it percolates
through the soil and helps recharge the groundwater.
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