Understanding the Septic System

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Private septic systems are designed to receive and decompose the household waste discharged from drains, washing machines and toilets. When correctly sited and installed, properly designed systems will efficiently renovate domestic waste water and sewage and return good quality water to the watershed. When operating incorrectly, private septic systems can allow pollutants to enter the groundwater. In conjunction with proper installation and maintenance, soil conditions are of particular importance in functioning of septic systems.

Soils with slow percolation rates, shallow restrictive soils and those over permeable impervious bedrock are inappropriate for such sewage disposal systems.

The system generally consists of a tank where sewage is received and treated before being discharged to one or more leaching systems beyond. The most common types of leaching systems are trenches, galleries and plastic chambers. A new type of leaching system is the Living Filter, manufactured by Form Cell.

If you have recently purchased your house and do not have information on your septic system, you will need to locate your tank before you can inspect, clean and properly maintain it.

If you do not know where your tank is, you may be able to obtain a copy of the final sketch of the plan for original installation of the system, the “as-built,” from the Westport Weston Health District or from the previous owner, septic pumper or builder. On file at the Health District offices are most “as-builts” for systems installed in Weston from 1966 to the present and in Westport from 1960 to the present. Homeowners may request a file search for such records at the Health District office.

Keep a copy of your “as-built” sketch and any subsequently approved applications for repair to your system in your household file.

If no “as-built” is on file or if your system was built prior to these dates, you may be able to find the septic pumper who last cleaned your tank by telephoning local licensed pumpers. If you do not succeed in obtaining this information, a licensed septic pumper can help you in locating the tank. Once you have located the tank, prepare a sketch of its location and keep a copy of this sketch in your household file. Also, please supply the Health District with a copy so a file for your property can be opened.Download Septic Care and Maintenance for the homeowner [PDF].  For an amusing video about septic systems produced by Staples High School students several years go,follow this link Pump It Up Baby.


Inspection and cleaning

It is prudent for a new homeowner to inspect the septic system with a licensed septic installer, determine whether it needs pumping, and establish an appropriate interval for routine inspection and cleaning. As a rule, septic tanks should be pumped out every three years. In situations involving heavy use or small capacity tanks, more frequent pumping may be necessary. Routine yearly inspection of the tank and baffles by the homeowner or a trusted serviceman is advisable to protect the life of the system. Septic tank outlet baffles prevent floating scum and sludge from discharging (or escaping) to the leaching system, and it is important that these baffles be inspected each time the tank is pumped.

Pumping is necessary before the sludge or scum accumulates to a point where it interferes with the effective settling function of the tank. The discharge of sludge or scum through the outlet piping into the leaching area can clog the leaching system. Clogging will lead to permanent failure of the system and a costly repair or replacement of the septic tank, the leaching area, or both. Besides the inconvenience and expense of such a mishap, an overflowing tank or leaching area presents a serious environmental health hazard since the escape of raw sewage can contaminate the ground and surface water in the area.

When the sludge or scum layer approaches the vicinity of the outlet baffle, the tank should be pumped out completely and the sludge removed from the bottom. The sludge is generally removed in the pumping process by stirring. It is not necessary to disinfect the tank, but it will not cause harm.


The following are guidelines that will minimize cleaning and maintenance costs and extend the life of your system.

Take care of the surface above the septic system

The area above the entire septic system should be kept clear, unpaved and unencumbered by anything (automobiles) which could damage the structure or interfere with evaporation. The ground above the leaching fields should be kept mowed and raked to allow for maximum evaporation. There should be no trees or shrubbery planted over this area since their shade would inhibit evaporation and their roots could eventually infiltrate and damage the leaching structures.

Runoff from precipitation should be diverted away from the septic area to prevent its impeding evaporation from the leaching area. Roof and foundation drains, sump pumps and water softener discharges should not be piped into the septic tank, since such large volumes of water will stir up the contents of the tank and carry some of the solids into the outlet line, in addition to hydraulically overloading the leaching system. For homes in Westport, the gutter storm water drains required by the town should not be near the septic system.

Be careful about what is disposed of through household drains

Avoid discharge of excess amounts of water into the system. Install water-saving shower heads. Place a brick or closed plastic bottle full of water in the toilet tank to decrease the amount of water used in flushing. New toilet fixtures work efficiently, using 1.6 to 2.5 gallons per flush. Backwash from household or swimming pool water filtering and softening systems may not be discharged into any subsurface disposal system.

Use direction even in disposing of biodegradable materials. Plain white toilet paper can be decomposed by the bacteria in the tank. Colored toilet paper cannot, and it adds to the sludge layer. Garbage disposals can put undue organic burden on the tank and are not allowed for use in Westport and Weston.

Some items which decompose very slowly (paper towels, feminine hygiene products and coffee grounds) should be avoided.

Some household chemicals (antifreeze, cleaners, disinfectants and antiseptics, oil-based paint, lacquer, varnish, wood, preservative, pesticides, poisons, paint removers, polishes, waxes, gasoline, acids and strong bases) are toxic to the bacteria in the septic tank and can adversely affect the system, allowing the discharge of raw sewage into the leaching fields, as well as polluting the ground water which you and your neighbors depend upon as a drinking water source.

Warning signs of system in danger of failure

Poor drainage of waste pipes from house. The sludge or scum layers approaching the vicinity of the outlet pipe. This is determined by removing the tank cover and inspecting the contents of the tank.

  • Broken or deteriorated inlet or outlet baffles.
  • Leakage of raw or semi-decomposed sewage on the ground in the vicinity of the septic tank and leaching area.

Protect yourself and your septic system

Proper upkeep and care of your septic system are essential for your own health as well as that of your neighbors and the surrounding environment. It is important to be aware of the current status of your system and to effect the necessary maintenance procedures when they are needed. In this way, you will help protect yourself against the possible health hazards and costly repairs that can arise through inadequate care of your septic system.