goes when you're done taking a
shower or using the bathroom? If your property is
connected to public sewer, then it goes to a sewage treatment
plant before being discharged to a body of water. But for people
who do not have access to public sewer, the answer is a private
onsite sewage disposal system, also known as a septic system.
In Fairfax County, there are more than 22,000 parcels with
private onsite sewage systems. It's important that homeowners
served by a septic system Think at the Sink. By
understanding how these systems work and what to do to keep them
running properly, you'll be maintaining your property
values, protecting the environment and keeping you and
your neighbors healthy. Traditional, or conventional,
onsite sewage systems consist of a treatment unit such as a
septic tank and a dispersal area or drain field. For home sites
that have space limitations or more challenging soil
conditions, an alternative system may be necessary. These
systems consist of an alternative treatment unit, and
a soil absorption area or other method of dispersal. Let's
look at the components of a conventional onsite sewage
system more closely. Here we see a new single-family dwelling
under construction That four-inch pipe coming out from
the house foundation is the sewer line. It carries the
wastewater from its point of use a sink, a bathtub, a toilet
to the septic tank. The septic tank itself is located
underground, outside of the home. This tank is pretty large
and, depending on the number of bedrooms in the home, could hold
as much as 2,700 gallons of wastewater. The septic tank is
sized in such a fashion to hold the peak amount of wastewater
generated in one day for 24-48 hours. The wastewater used in
one day is slowly anaerobically digested and pushed across the
tank over that time frame. The resulting raw or partially
treated sewage then goes out to the dispersal area or is stored
temporarily until it gets pumped to the dispersal area, where it
is absorbed in the soil. Now let's look at the dispersal
area. The dispersal area is an area that has been designed to
accommodate the peak daily flow of wastewater for that dwelling
or building, as determined by Soil Evaluators, Professional or
Certified Soil Scientists, or Professional Engineers. The
dispersal area could be conventional trenches, a pad,
low pressure distribution, drip, or even an above grade mound.
Ultimately the size of the dispersal area will depend on
how many bedrooms in the house or dwelling, or how much
wastewater a commercial building can generate. Some systems
require a pump station to pump the wastewater to the dispersal
area. This is done for one of two reasons: the first is to
overcome gravity; it is difficult to make water flow up
hill on its own; the next is to control how much sewage goes out
to the dispersal area. Now that you know how onsite sewage
systems work, it's important to understand how best to
maintain them. Proper maintenance can help extend the
life of these systems beyond the typical 20 years. First,
you'll need to pump your septic tank or treatment unit
out at a minimum of once every five years. Be sure to notify
the Health Department each time the tank is pumped. Second, if
you have a flow diversion valve, as many septic systems in
Fairfax County do, you'll also need to turn that valve
annually. If you have an alternative onsite sewage
system, you'll have additional maintenance to do. At a minimum
you'll need to have the system inspected annually and have
testing done every five years. You'll also want to refer to
the Operations and Maintenance Manual that was provided when
the system was approved for additional maintenance steps.
Whether you have a traditional or alternative system, you'll
Don't overload the septic system with too much water by
using high-efficiency toilets, spacing the laundry out
over the week, and minimizing the use of garbage disposals.
Don't put harsh chemicals such as bleach, fats, oils or grease
down the sink. Don't plant trees on top of or within 10
feet of the septic tank or drain field. Don't drive over your
septic tank or pump chamber. And keep good maintenance records.
When you have any repairs or maintenance done to your system,
be sure that you use a licensed contractor. Contractors can be
verified by contacting the Health Department. So next time
you flush the toilet or empty the bathtub, remember that what
goes down the drain affects how well your septic system works.
Think at the Sink!