Septic Information
A septic system is a sewage treatment and disposal system buried in the ground. It is
composed of a septic tank and a leach field or trench. Household sewage (wastewater from
sinks, toilets, showers, washing machines, garbage grinders, and dishwashers) generally
flows by gravity into the septic tank. There, heavier particles settle to the bottom and
scum rises to the top. Bacteria in the tank help break down some of the solids. The sludge
and scum remain in the tank, and the effluent (liquid) flows to the leach field, where it
is distributed over crushed gravel or absorbent soil. The liquid typically includes
contaminants such as nitrates, phosphorus, disease causing bacteria and viruses, dissolved
metals, detergents, and solvents. The septic tank and leach field provide a minimal
treatment for these contaminants. Generally phosphorus and dissolved metals are bound by
the soil - although sandy and gravelly soil may not remove these compounds, a point that
will be returned to later. Nitrates and solvents are diluted in groundwater. Bacteria and
viruses are filtered by the soil or die off. But septic systems can fail - due to poor
design or construction, to overloading, or to inadequate maintenance.
What Makes a Septic System Fail?
There are two types of septic system failure. Hydraulic failure occurs when the soil
cannot handle the volume of wastewater, and as a result sewage overflows onto the ground
or backs up into the house. This is caused by: Failure to pump out the tank. Wastewater
will back up into the house or break out onto the ground when sludge and scum from an
overfull tank flows into the leach field and clogs the soil. Poorly sited or built
systems. When the septic system is sited in or too close to the high water
table, or is constructed with improper fill, saturated soil can cause wastewater to back
up or break out. This is particularly likely to occur in the spring, when the water table
is high. Tree and bush roots. Tree and bush roots over a leach field can break or block
pipes and interfere with the distribution system.
Do's and Don'ts
Do:
•Inspect your tank for signs of sludge buildup and make sure the baffles and tees are
in working order.
•Pump your tank as needed (every 2-3 years for year-round residences, and every 4-5
years for seasonal residences), and keep a written record for yourself or the future
owner.
•Compost food garbage or put it in the trash.
•Keep a grease can handy.
•Mark your septic system so you can protect it from vehicles and encroaching trees
and shrubs.
•Conserve water; install water-saving devices, such as low flow faucet and shower
heads.
•Use non-toxic cleaning products such as baking soda to scrub toilets, or boiling
water to help clear clogged drains.
•Contact a site evaluator if your septic system shows signs of failure; contact your
local plumbing inspector if you see evidence of other malfunctioning septic systems.
•Request that your site evaluator design a loam liner for your leaching field if the
site has sandy soil.
•Plant shrubs, trees, and grasses downhill from your system to act as a sponge (it
will tie up excess nutrients and water as well as prevent soil erosion).
Don't:
•Don't use a garbage disposal - it adds 50 percent more solids to your system.
•Don't pour automotive oil, cooking oil, or grease down the drain.
•Don't drive vehicles over the septic system or leach field.
•Don't plant bushes or trees over the leach field.
•Don't use phosphorus detergents.
•Don't use too much water, especially during rainy, wet seasons when the ground is
saturated.
•Don't pour paint or paint thinner into your sink (let it air dry then throw it out
in the trash).
•Don't use drain cleaners and other toxic chemical products.
•Don't use chemical or biological septic system cleaners which can plug up leach
fields and ruin your system.
•Don't wait - if your septic system shows signs of problems, act immediately.
For more information to your questions
E-mail us at compost@midcoast.com
or call 1-800-596-5646.