University of Maryland Extension

FAQ on Septic Systems

Frequently Asked Questions on Septic Systems

  • Where can I locate information to determine what type of septic installation is on my  property? Your County Health Department maintains records of permitted systems and you may request those records by conducting them. Click here for a list of County offices in Maryland.
  • I know where my septic tank located but I’m not sure where my drain field is located. Where do I go to find the location of the drain field? Is it important for me to know where my drain is located?Again, your County Health Department maintains records of permitted systems. Knowing the location of your drain field is important, as you do not want to do anything over it that could damage it, such as, planting trees, paving over it or driving over it. You also do not want to plant a vegetable garden over it. Are the installation of septic tanks regulated? And if so, by whom? Installation of septic systems are regulated by County Health Departments under delegated authority from the Maryland Department of the Environment (MDE)
  • What is a perc test and why does it need to be done.  A percolation test (or perc test) is a component of an overall site evaluation that is conducted to determine permeability of soils and geology. During a perc test and site evaluation, limiting factors within the soils and geology are identified such as groundwater levels, consolidated material that will not allow water to permeate, as well as soil texture, structure and consistence. Perc tests help to determine the most suitable design for a drainfield to serve as a component of the overall septic system.
  • How long will my septic last, before it needs to be replaced?  Septic systems typically last 20 to 30 years before needing replacement. If the system has not been properly maintained, is being infiltrated by surface or groundwater, has been invaded by tree roots, or has otherwise been misused, this time frame may be shorter.
  • What signs should I look for to determine if my septic tank needs to be replaced?  Signs that your septic system is not performing as designed include: slow drains, surfacing effluent (wet spots in the yard or near the tank), sewage backing up into a bathtub or basement drain (usually on a lower level of the house), a sounding alarm (pump system or BAT), unexplained illness, or foul odors.
  • How often should a septic tank be pumped?  The frequency of pumping for conventional septic tanks depends on the size of the tank and the number of occupants in the home. BAT units require special pumping methods and frequency is unit dependent – contact your BAT service provider or installer for more information.
  • Where are the filters in a septic system and who should replace them, the homeowners or a professional?  Not all septic tanks have a filter in the septic tank, but if your septic tank is one that does have one, cleaning or replacement of these filters should be left to the professionals to maintain on at least an annual basis.
  • Why do septic need to be pumped? Are liquids released via the septic tank?  Septic tanks need to be pumped because solids and FOG (fats, oils and grease) accumulate in the tank. When septic tanks are not pumped on a proper schedule, the solids and FOG eventually build up to the point that they are released into the drainfield where clogging of the drainfield can occur. This usually leads to costly system replacement, so it is very important to pump you tank. Think of it as an oil change in your car. If you don't change your oil, the car will still work for a while but one day it will blow up and leave you stranded.
  • What is a reasonable cost to have septic tank pumped?  Typical costs for septic tank pumping is between $250-400 depending on size of tank and location.
  • What type of waste will not decompose in a septic tank?  It is very important to not dispose of chemicals, paint, grease, food or anything that is not bodily waste, toilet paper, or wastewater from showering, handwashing, dishwashing or laundry.
  • My septic has not been pumped in 15 years. How often should a septic be pumped considering I have been the only person living in residence?  It depends on the size of the tank. If you have not pumped the tank for 15 years, you have almost certainly waited too long and may have been unknowingly causing damage to your drain field. It is suggested that you pump your tank as soon as possible to prevent further damage to your drain field. Listen to what your pumper has to say about the state of your septic tank when they pump it. This will guide your decision about pumping in the future – it is recommended not going longer than 5 years between pump outs.
  • Is the use of a garbage disposal detrimental to a septic tank? If not, are there any types of food items that should not be place in a garbage disposal?  Absolutely. We do not advise the use of garbage disposals when served by on-site sewage disposal. The ground up food wastes are not broken down effectively in the tank and may enter the drainfield, resulting in premature clogging and failure.
  • Should people believe the packaging on toilet paper and other products that state they are septic system safe?  Most toilet paper is safe for septic systems, although some in the industry do argue that the paper with lotions and aloe don't break down as easily. However, wet wipes or wipes of any kind should not be disposed of down the drain (even those that claim to be flushable).
  • Can you use cleaners, such as bleach, daily in toilets?  One property of many cleaners is to kill bacteria. If you are flushing these types of cleaners down the drain, you are essentially killing off the beneficial bacteria in your septic system – making it less efficient. It is recognized that household bathroom and kitchens require routine cleaning to maintain a healthy home and so minimal use is acceptable. Regular (daily) flushing of systems of bacteria killing cleaning products is NOT recommended.
  • What does the Bay Restoration Fund (BRF) fund cover?  Qualifications to received full or partial BRF funding is based on septic system status (failure vs new construction), location (in or out of critical area) and annual income (more or less than $300,000). Depending on your situation, the fund can cover any of the following:
    •  Pump-out of existing tank
    •  Crush & fill or removal of existing tank
    •  Installation of BAT system (DOES NOT cover the replacement of the drainfield)
    •  2-yrs of Operations and Maintenance for the BAT
    •  All permits
    •  Electrician and all electrical work (exception: need for addition of sub-panel)
    •  Final grading and seeding (DOES NOT cover landscaping restorations, including but not limited to the needed removal of decks, patios and fencing)
    •  Follow up visit
  • If you have a parcel of land and are considering building on it...can you use BRF for a new build?  The use of BRF funding to install BAT systems with new construction is not out of the question, however it is the lowest priority for the county. These low priority applications only happen when there is extra funding available after all higher priority applications are funded. Click here for more information about the BRF program. Note that applications for BRF funding are made to the County Health Departments.
  • Do you have any recommended installers?  As representatives of the University, we are not in the position to recommend specific installers. It is important to make sure that whomever you hire are certified to do the work you are contracting them to do (conventional septic system, BAT, drain field). Click here for a list of certified installers from MDE. Your County Health Department may have additional information.
  • When an older septic system has be replaced with a new conventional system or BAT system do you also have to replace the drain field?  No – not necessarily. The tank system and drain field are two different components of your septic system – one can become damaged (needing replacement) independent of the other. For example – should you have to replace your tank because it cracked due to settling or water seepage the new system could potentially be connected to your existing drain field.
  • What is recommended to plant on my drainfield?  Turfgrass such as fescue is what most homes have over their drainfields. Grasses and shallow rooted native plants including flowers are also acceptable the plants provide a beneficial service by taking up both water and nutrients. Trees, however, should not planted since the roots can enter the system and clog the pipes leading to a system failure.
  • What can I do to prolong the life of my drainfield?  Follow these maintenance tips:
    •  Conserve water – fix leaks, use water saving appliances
    •  Avoid garbage disposals and draining fats, oils and grease
    •  Detour water treatment backwash from septic system
    •  Don’t dispose of chemicals down drains
    •  Only flush toilet paper – no wipes, etc.
    •  Ensure stormwater runs away from tank and drainfield
    •  Keep traffic off of drainfield
    •  Don’t plant trees near tank or drainfield
    •  Have tank pumped every 2-5 years – conventional; BAT- per service provider
    •  Have tank filter cleaned regularly (if applicable)
    •  Do not disconnect power to BAT and continue service A BAT unit produces cleaner wastewater (less dissolved solids) than a conventional system and therefore can help a drainfield last longer.
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