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Septic System
How Septic
Systems Operate...
Households not served by public sewers usually depend on a septic system to
dispose of wastewater. There are many different types of septic systems designed
to fit a wide range of soil and site conditions. These include mound systems,
sand filter systems and pressure distribution systems. This guide should help
you understand the operation and maintenance of a conventional gravity-flow
septic system.
A conventional septic system consists of two main parts: the septic tank and
the soil drainfield (also referred to as a leachfield, absorption bed or
absorption field). At the head of the drainfield a distribution box or a
manifold distributes wastewater to several absorption trenches. Some locations
require that newly installed drainfields include a designated replacement area
should the existing septic system need an addition, repair or replacement, the
replacement area can then be used.
The septic tank. A septic tank is a large,
underground, watertight container, typically about 9 feet long, 4-5 feet wide
and 5 feet tall that is connected to the home's sewer line. While typically
designed with a 1,000-gallon liquid capacity, the size of the tank is determined
by the number of bedrooms in the home. Septic tanks may be rectangular or
cylindrical and may be made of concrete, fiberglass or polyethylene.
Raw waste water from the bathroom, kitchen and laundry room flows into the
tank where the solids separate from the liquid. Light solids, such as soap suds
and fat, float to the top and form a scum layer. This layer remains on top and
gradually thickens until you have the tank cleaned. The liquid waste goes into
the drainfield, while the heavier solids settle to the bottom of the tank where
they are gradually decomposed by bacteria. But some non-decomposed solids
remain, forming a sludge layer that eventually must be pumped out.
Septic tanks may have one or two compartments. Two-compartment tanks do a
better job of settling solids and are required in some areas for new
installations. Tees or baffles at the tank's inlet pipe slow the incoming wastes
and reduce disturbance of the settled sludge. A tee or baffle at the outlet
keeps the solids or scum in the tank. All tanks should have accessible covers
for checking the condition of the baffles and for pumping both compartments
.
The Drainfield. Further treatment of wastewater occurs in the soil
beneath the drainfield. The drainfield consists of long underground perforated
pipes or tiles connected to the septic tank. The network of pipes is laid in
gravel-filled trenches (2-3 feet wide), or beds (over 3 feet wide) in the soil.
Liquid waste or effluent flows out of the tank and is evenly distributed into
the soil through the piping system. The soil below the drain-field provides the
final treatment and disposal of the septic tank effluent. After the effluent has
passed into the soil, most of it percolates downward and outward, eventually
entering the groundwater. A small percentage is taken up by plants through their
roots, or evaporates from the soil.
The soil filters the effluent as it passes through the pore spaces. Chemical
and biological processes treat the effluent before it reaches groundwater, or a
restrictive layer, such as hardpan, bedrock, or clay soils. These processes work
best where the soil is somewhat dry and permeable, and contains plenty of oxygen
for several feet below the drain field. The size and type of drainfield depends
on the estimated daily wastewater flow and soil conditions.
What is septic system failure?
A septic system should effectively accept liquid wastes from your house and
prevent biological and nutrient contaminants from getting into your well or
nearby lakes and streams. Anytime these things do not happen, the system is
failing.
For example, when waste backs up in your backyard, the system has obviously
failed. If significant amounts of biological or nutrient contaminants reach your
well or surface waters, the system is also failing, even though it may appear to
be working just fine.
Why septic systems fail?
Most septic systems are designed to have a lifetime of 20 to 30 years, under the
best conditions. However, many septic systems will fail before this time.
Eventually, the soil around the absorption field becomes clogged with organic
material, making the system unusable.
Many other factors can cause the system to fail well before the end of its
"design" lifetime. Pipes blocked by roots, soils saturated by storm
water, crushed tile, improper location, poor original design or poor
installation can all lead to major problems.
But by far the most common reason for early failure is improper maintenance
by homeowners. When a system is poorly maintained and not pumped out on a
regular basis, sludge (solid material) builds up inside the septic tank, then
flows into the absorption field, clogging it beyond repair.
Some inspection companies advertise they do septic inspections when in fact
all they do is drop some dye tablets into the toilet. This will tell you nothing
about how the system is handling the waste or if there is a blockage anywhere in
the system. And they have the nerve to charge you for it!
Due to the Home Inspection Professional Licensing Act
Home Inspectors can no longer perform this service.
If the home you have an interest in has a private disposal system, don't take
any chances, have it inspected. Call us, I will help you find a qualified
company to perform his service.
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NEW JERSEY 