Guide Caring for Your Septic System

Septic systems are individual wastewater treatment systems, usually for individual homes. They are typically used in rural or lot settings where central wastewater treatment is not efficient.

What is a Septic System?

Septic systems are individual wastewater treatment systems (conventional septic systems, innovative/alternative (I/A) systems, or cesspools) that use the soil to treat small wastewater flows, usually from individual homes. They are typically used in rural or large lot settings where centralized wastewater treatment is impractical.

There are many types of septic systems in use today. While all systems are individually designed for each site, most systems are based on the same principles.

A conventional septic system consists of a septic tank, a distribution box and a drainfield, all connected by pipes, called conveyance lines.

Your septic system treats your household wastewater by temporarily holding it in the septic tank where heavy solids and lighter scum are allowed to separate from the wastewater. This separation process is known as primary treatment. The solids stored in the tank are decomposed by bacteria and later removed, along with the lighter scum, by a professional septic tank pumper.

After partially treated wastewater leaves the tank, it flows into a distribution box, which separates this flow evenly into a network of drainfield trenches. Drainage holes at the bottom of each line allow the wastewater to drain into gravel trenches for temporary storage. This effluent then slowly seeps into the subsurface soil where it is further treated and purified (secondary treatment). A properly functioning septic system does not pollute the groundwater.

How often should I pump out my septic system?

Regular maintenance is the most important thing in making sure your septic system works well.

Regular pumping helps prevent solids from escaping into the drainfield and clogging soil pores. While pumping frequency is a function of use, MassDEP recommends that systems be pumped at least once every three years for homes not having a garbage disposal. If the home's system has a garbage disposal, it should be pumped every year.

If you are a nonresidential system owner, you should determine how often to pump based on prior accumulation and pumping records. Often you can look at pumping intervals to gauge your pumping schedule (i.e., previously did you wait too long before having your tank pumped and it was filled to capacity, or could you have waited a little longer to pump?).

An amazing number of system owners believe that if they haven't had any problems with their systems, they don't need to pump out their tanks. Unfortunately this is a serious and sometimes costly misconception. As your system is used, solid materials settle to the bottom of the tank, forming a sludge layer. Grease and lightweight materials float to the surface of the septic tank as scum.

Normally, properly designed tanks have enough space for up to three to five years' safe accumulation of sludge. When the sludge level increases beyond this point, sewage has less time to settle properly before leaving the tank. As the sludge level increases, more solid wastes escape into the soil absorption system (SAS). If the SAS becomes so clogged that it cannot absorb liquid at the rate at which it enters the tank, the plumbing will "back up" or unsanitary wastewater will bubble to the surface.

When hiring a pumper, be sure the local Board of Health has licensed them, and always make sure you get a paid receipt from the pumper that spells out the details of the transaction (how many gallons were pumped out of the tank, the date, the charges, and any other pertinent results). Retain this receipt for your records. The pumper sends a copy of this report to the local Board of Health.

Additional Resources

Failing Septic Systems Can Be Hazardous to Your Health

Septic systems that have been properly maintained helps prevent the spread of disease.

Failing systems can

  • cause a serious health threat to your family and neighbors,
  • degrade the environment, especially lakes, streams and groundwater,
  • reduce the value of your property,
  • be very expensive to repair,
  • and put thousands of water supply users at risk if you live in a public water supply watershed and fail to maintain your system.

Be alert to these warning signs of a failing system:

  • sewage surfacing over the drainfield (especially after storms),
  • sewage back-ups in the house,
  • lush, green growth over the drainfield,
  • slow draining toilets or drains,
  • sewage odors.

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