How Does a Septic System Work?

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 (waste water from sinks, toilets, showers, washing machines, garbage grinder, 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, phosphorous, 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. Nitrates and solvents are diluted in the groundwater. Bacteria and viruses are filtered by the soil or die off. Septic systems can fail due to poor design or construction, overloading or inadequate maintenance.

What Makes a Septic System Fail?

There are two types of septic system failure:
Hydraulic Failure — This 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 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 waste water to back up or break out. This is particularly likely to occur in the spring when the water table is high. Tree and brush roots over a leach field can also break or block pipes and interfere with the distribution system.

How Do I find My Septic Tank?

Generally, you find your outgoing pipe in the cellar and measure outside 9 to 12 feet from the foundation wall where the pipe exits. This is not always the case but is a good starting point.

Having a Problem?

If you are having issues with 1 or 2 fixtures in your house, contact a plumber. If you are having trouble with all fixtures in your house it may be a septic issue, give us a call 207.596.5646 or 1.800.596.5646.

3 Questions We Ask

  1. Do you have a pump? (Check for tripped circuit breaker)
  2. Do you have an outlet filter?
  3. When was the last time the tank was pumped out?

Do’s and Don’ts


  • 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 3 Years for a Family of 4
    — Every 5 Years for a Family of 2
  • Seasonal residence would depend on amount of people and duration of visit
  • Keep a written record for yourself or the future owner
  • Pump tank when solids are one third of the volume
  • 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 faucets and shower heads
  • Use non-toxic cleaning products such as baking soda to scrub toilets or boiling water to help clear clogged drains
  • Clean your filter (if you have one) every 6-12 months


  • Don’t use a garbage disposal, it adds 50% 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 septic system or 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