Septic System Care

What Type of System Do You Have?

Most older homes have conventional septic systems. However, some
may still have cesspools (a large brick, stone or concrete vault where
solids can settle and liquid can leak out) or a seepage pit (a septic tank
connected to a dry well or pre-cast tank with holes surrounded by gravel)
or even a privy. Cesspools and seepage pits were popular prior to the
1950s, but they are no longer allowed in most areas of the country. A
privy, or an outhouse, is simply a structure built around a hole in the
ground that can be relocated when the hole is full - these are usually
illegal, although some may be found in remote areas.

The first step is to determine what kind of system you have. This is not
always easy since these systems are all buried in the ground. Go in the
basement or crawlspace and try to determine the direction that the
wastewater pipe is exiting the house. Also look for pipes or covers
protruding from the soil. In winter, the soil over the tank is usually the
last to be covered by snow and the first place where snow melts (this
sometimes happens over the disposal field as well, but often the liquid
has cooled enough to have little effect). If you cannot find the system,
contact your local health department, which may have record of its
installation, or you may need to hire a septic-system inspector to identify
the type and location. Some newer systems, particularly in areas where
the water table is high or where there is too much clay in the soil to allow
the water to seep through, may have a large mound in the yard. In this
case, the disposal field is actually located within the mound in order to
provide enough soil to filter out pollutants.

How Does a Septic System Work?

The typical septic system includes a septic tank (or tanks), typically
about 9 feet long, 4 to 5 feet wide and 5 feet tall, that is designed to
capture solids from household wastes, and a disposal field (also referred
to as a leach field, drainfield, absorption bed or absorption field), which is
designed to dispose of the liquid wastes. Wastes go from the toilet, sink,
shower or washer through the indoor plumbing to the septic tank. The
tank is a watertight, underground receptacle where the solid wastes are
broken down by bacteria. Septic tanks may be rectangular or cylindrical
and may be made of concrete, fiberglass or polyethylene. As the wastes
move through the tank, the solids settle to the bottom and form a layer of
sludge, while the liquids pass through the outlet pipe. Anaerobic bacteria
(bacteria that live in the absence of free oxygen) decompose the solid
wastes over time.

As the liquid passes through the tank, lighter particles and grease rise to the surface to form a floating scum layer that remains in
the tank. The liquid that passes through the tanks still contains large concentrations of harmful bacteria and organic matter. The
liquid then goes through the outlet pipe to a distribution box or a manifold, which distributes wastewater to perforated or open-
jointed pipes buried in shallow, gravel-filled trenches. Baffles installed at the outlet help prevent solids and scum from leaving the
tank and entering the disposal field. Liquid waste, or effluent, flows out of the pipes and is evenly distributed into the soil through
the disposal system. The soil below the drain field provides the final treatment and disposal of the septic tank's 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 septic tank may be either single, divided or dual. It should have at least one inspection port (a pipe with a cover), and a
pumpout port covered by a small manhole cover (although this may be below the ground surface).

Why Do 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.

Solids are always accumulating in the septic tank because the rate of decomposition is much slower than the rate at which sewage is
added. In addition, some solids will never decompose. Also the fats and grease that form the scum layer will accumulate faster than
the rate of decomposition. This scum layer is held in the tank by the baffles. If the baffles become damaged, the scum may enter the
disposal pipes and cause them to clog and malfunction. Failures may also occur if you dispose of inert, toxic or non-biodegradable
substances into your system. These materials will not decompose and may either kill the good bacteria or simply clog the tank.

Additionally, large surges to the system from too much usage (like the party your teenagers have when you are away) can either
cause an overflow or disturb the balance of the system. Water overload occurs when the disposal field is flooded with more water
than it can effectively absorb, thereby reducing the ability of the system to drain wastes and filter sewage before it reaches
groundwater. It also increases the risk that effluent will pool on the ground surface and run off into surface water or down nearby
water well casings