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.

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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.

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How often should I pump out my septic system?

MassDEP recommends that a properly maintained septic system should be pumped out at least once every 3 years!

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 3 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 3 to 5 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.

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Septic System Do's and Don'ts

Do...

  • Have the system inspected and pumped every 3 to 5 years. If the tank fills up with an excess of solids, the wastewater will not have enough time to settle in the tank. These excess solids will then pass on to the leach field, where they will clog the drain lines and soil.
  • Know the location of the septic system and drain field, and keep a record of all inspections, pumpings, repairs, contract or engineering work for future references. Keep a sketch of it handy for service visits.
  • Grow grass or small plants (not trees or shrubs) above the septic system to hold the drain field in place. Water conservation through creative landscaping is a great way to control excess runoff.
  • Install water-conserving devices in faucets, showerheads and toilets to reduce the volume of water running into the septic system. Repair dripping faucets and leaking toilets, run washing machines and dishwashers only when full, and avoid long showers.
  • Divert roof drains and surface water from driveways and hillsides away from the septic system. Keep sump pumps and house footing drains away from the system as well.
  • Take leftover hazardous chemicals to your approved hazardous waste collection center for disposal. Use bleach, disinfectants, and drain and toilet bowl cleaners sparingly and in accordance with product labels.
  • Use only septic system additives that have been allowed for use in Massachusetts by MassDEP. Additives that are allowed for use in Massachusetts have been determined not to produce a harmful effect to the individual system or its components or to the environment at large.

Don’t...

  • Use your toilet or sink as a trash can by dumping non-biodegradables (cigarette butts, diapers, feminine products, etc.) or grease down your sink or toilet. Non-biodegradables can clog the pipes, while grease can thicken and clog the pipes. Store cooking oils, fats, and grease in a can for disposal in the garbage.
  • Put paint thinner, polyurethane, anti-freeze, pesticides, some dyes, disinfectants, water softeners, and other strong chemicals into the system. These can cause major upsets in the septic tank by killing the biological part of your septic system and polluting the groundwater. Small amounts of standard household cleaners, drain cleansers, detergents, etc. will be diluted in the tank and should cause no damage to the system.
  • Use a garbage grinder or disposal, which feeds into the septic tank. If you do have one in the house, severely limit its use. Adding food wastes or other solids reduces your system's capacity and increases the need to pump the septic tank. If you use a grinder, the system must be pumped more often.
  • Plant trees within 30 feet of your system, or park/drive over any part of the system. Tree roots will clog your pipes, and heavy vehicles may cause your drainfield to collapse.
  • Allow anyone to repair or pump your system without first checking that they are licensed system professionals.
  • Run excessive laundry loads with your washing machine. Doing load after load does not allow your septic tank time to adequately treat wastes and overwhelms the entire system with excess wastewater. You could therefore be flooding your drain field without allowing sufficient recovery time. You should consult your tank professional to determine the gallon capacity and number of loads per day that can safely go into the system.
  • Use chemical solvents to clean the plumbing or septic system. “Miracle” chemicals will kill microorganisms that consume harmful wastes. These products can also cause groundwater contamination.

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Failing Septic Systems Can Be Hazardous to Your Health

Septic systems that have been properly maintained help 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.

If  your system fails, the first thing you should do is contact your local board of health, which needs to approve all upgrades and most repairs. The board of health will tell you what you will need to do.

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