Septic systems

When properly designed, installed and maintained, septic systems can have a minimum life expectancy of 20 to 30 years.

The Basic Design

A septic system usually consists of 3 main components:

  • Septic tank
  • Distribution Box
  • Soil Absorption System (SAS) – a system of trenches, galleries, beds, chambers or pits which receives effluent from the septic tank or distribution box and transmits it to the soil.

Wastewater drains from the house, via a sewer pipe to the septic tank. There, it is kept for a day or more to allow the solids in the wastewater to separate from the liquids. The layers of scum and sludge remain in the septic tank where bacteria found naturally in the wastewater work to break down the solids. Gases are released through a plumbing vent located on the roof of the house.

After the wastewater is allowed to settle and separate in the septic tank, the partially treated liquid flows out of the tank and into the distribution box where it is uniformly distributed into the Soil Absorption System (SAS) below the surface of the ground.

The SAS treats the wastewater by allowing it to slowly trickle from perforated pipes or chambers into a layer of stone and then down through sand and soil. The stone and soil in an SAS act as biological filters to remove toxins, bacteria, viruses and other pollutants from the wastewater. It is this filtering process, along with the biological action, that cleanses the liquid so that it is made potable by the time it reaches the aquifer and drinking water supply.

Title 5 Inspections

Title 5 of the Massachusetts State Environmental Code requires that all septic systems be inspected by a certified inspector at the time of transfer of property, change of use, or expansion.

The regulations require an inspection to be conducted anytime within the two years before the sale, or six months after the sale if weather conditions precluded prior inspection. If the system has been pumped on an annual basis, then the inspection is valid for three years.

In Conway, Board of Health regulations require that the inspection be witnessed by an agent of the BOH. They also require that the drinking water be tested for coliform, lead, nitrates and nitrites.

Caring for your System

Generally speaking, septic tanks should be pumped every 2 to 4 years, depending upon usage. Frequent pumping will disrupt the bacterial action of the system. And, not pumping frequently enough will allow for clogging to occur. (It’s a good idea to keep an accurate record of service to the septic system, including pumping and filter cleaning.) Garbage grinders are strongly discouraged from use with septic systems as they require a larger SAS. However, if they are used, the tank should be pumped every year.

In many systems installed since about 1997, effluent filters have been placed in the septic tank outlet pipe to trap solids and keep them from carrying over and clogging the SAS. If a filter is present, it should be rinsed off when the tank is pumped. If not cleaned periodically, the filter can cause a backup of liquids in the system.

To keep your septic system operating properly, follow these general guidelines. Do not flush or put any foreign or non-degradable items down the drain, including:

  • Items that will clog the pipes, such as diapers, feminine hygiene products, condoms, cat litter, cigarette filters, plastics, coffee grinds, paper towels, grease, dental floss, or scraps of food.
  • Even if you have a garbage grinder, do not process such items as onion skins, apple peels, bean hulls, egg shells or other items that are difficult to dissolve.
  • Bacteria killers such as household chemicals, water softeners, antiseptics, gasoline, oil, pesticides, antifreeze, latex or oil based paints, paint thinners or other solvents. These chemicals will kill the beneficial bacterial action necessary to treat your wastewater.
  • Do not allow driving, parking or paving over the SAS.

Danger Signals

Be alert to these potential warning signs of a failing septic system.

  • Sewage odors – toxic gases, including methane and hydrogen sulfide, are produced by the natural treatment processes in septic tanks. It is important to make sure the septic system is properly vented through the roof of the house. Extreme care should be taken if any septic smells are detected within the house.
  • Slow draining toilets or drains.
  • Sewage backups in the house plumbing system.
  • Sewage or black water accumulating or ponding over or around the SAS, especially during wet seasons or after a rain storm.
  • Areas of beautiful green grass over the septic field. This may be pretty, but a warning sign.

Septic Additives

If not abused, septic systems depend on natural processes and are self-sufficient. They normally do not need any additives or chemical enhancements. In fact, it is against Department of Environmental Protection regulations to introduce any additives that are not specifically approved by the DEP. For the approved list, see their website at

Landscaping Septic Systems

Grasses are the most recommended type of vegetation above the SAS to help with oxygen exchange and evaporation. Meadow grasses mixed with wildflowers may also be a good choice because they don’t have to be mowed regularly. Care should be taken to avoid digging or placing any trees or plants nearby that would allow the infiltration of roots into the SAS. This might breach the leach facility and possibly damage or break the pipes.

Also, do not build any structures like decks, sheds or patios over any of the system components, which would make it difficult to access the system.

Some systems are designed to include vent pipes as part of the leach field. These are usually four inch PVC pipes that rise above the ground and are affectionately known as “candy canes.” Some people view these pipes as opportunities to creatively plant vines, build stone sculptures, or place a trellis or other artistic disguises.