How Does a Septic Tank Work? A Unique Perspective

HOW DOES A SEPTIC TANK WORK? A UNIQUE PERSPECTIVE

Septic systems, also known as onsite wastewater treatment systems, play a crucial role in treating wastewater for homes, businesses, and small communities. These systems are well-established and effective, serving more than 420,000 homes in Maryland alone1. In this blog, we’ll explore the inner workings of septic tanks, their components, and how they contribute to environmental health.


The Essential Components


1. The Septic Tank


THE SEPTIC TANK IS THE HEART OF THE SYSTEM. IT’S LIKE THE QUIET HERO THAT DUTIFULLY HANDLES OUR WASTEWATER. CONSTRUCTED FROM CONCRETE, FIBERGLASS, OR PLASTIC, THE TANK IS A WATERTIGHT CONTAINER DESIGNED FOR SEVERAL PURPOSES:


  • TEMPORARY STORAGE: WASTEWATER ENTERS THE TANK THROUGH AN INLET. INSIDE, SOLIDS, FATS, AND GREASE SETTLE TO THE BOTTOM, FORMING A LAYER OF SLUDGE. MEANWHILE, THE LIQUID PORTION (EFFLUENT) RISES TO THE TOP.
  • PARTIAL TREATMENT: SOME DECOMPOSITION OF SOLIDS OCCURS IN THE SEPTIC TANK. HOWEVER, THE REAL MAGIC HAPPENS OUTSIDE THE TANK.


2. The Soil Absorption Component

THIS IS WHERE THE SOIL COMES INTO PLAY. THE SOIL ABSORPTION COMPONENT, OFTEN CALLED THE DRAINFIELD, DISTRIBUTES THE LIQUID EFFLUENT OVER A PREDETERMINED AREA OF SOIL. BENEATH THE DRAINFIELD LIES THE NATURAL SOIL, WHICH ACTS AS THE FINAL TREATMENT ZONE. HERE’S HOW IT WORKS:


  1. DISTRIBUTION BOX: IN A CONVENTIONAL SEPTIC SYSTEM, A DISTRIBUTION BOX ENSURES EVEN DISTRIBUTION OF WASTEWATER AMONG THE TRENCHES. THINK OF IT AS THE TRAFFIC COP DIRECTING EFFLUENT FLOW.
  2. BENEFICIAL BACTERIA: AS THE EFFLUENT PERCOLATES THROUGH THE SOIL, BENEFICIAL BACTERIA GET TO WORK. THEY FEAST ON THE REMAINING SOLIDS AND NUTRIENTS, INCLUDING NITROGEN.
  3. PATHOGEN ELIMINATION: THE BACTERIAL DECOMPOSITION REDUCES PATHOGENS HARMFUL TO HUMAN HEALTH.


Environmental Impact


Septic systems are one of the sources of excess nutrients in the Chesapeake Bay watershed, which is said to be one of "America's dying bodies of water".


  • NITROGEN CAN NEGATIVELY IMPACT THE WATER QUALITY OF THE CHESAPEAKE BAY BY CAUSING TOO MUCH ALGAE TO GROW. ALGAE ARE TINY PLANTS THAT LIVE IN THE WATER AND USE SUNLIGHT AND NUTRIENTS TO MAKE THEIR OWN FOOD. WHEN THERE IS TOO MUCH ALGAE, THEY BLOCK THE SUNLIGHT FROM REACHING THE PLANTS THAT GROW UNDER THE WATER, SUCH AS UNDERWATER GRASSES. THESE PLANTS ARE IMPORTANT FOR PROVIDING FOOD AND SHELTER FOR FISH AND OTHER ANIMALS THAT LIVE IN THE BAY. WHEN THE ALGAE DIE, THEY ARE DECOMPOSED BY BACTERIA THAT USE UP THE OXYGEN IN THE WATER. THIS CREATES AREAS OF LOW OR NO OXYGEN, CALLED DEAD ZONES, WHERE FISH AND OTHER ANIMALS CANNOT SURVIVE. NITROGEN CAN ALSO AFFECT THE QUALITY OF THE GROUNDWATER, WHICH IS THE WATER THAT IS STORED UNDER THE GROUND AND CAN BE USED FOR DRINKING OR IRRIGATION.
  • APPROXIMATELY 6% OF THE TOTAL NITROGEN LOAD TO THE BAY COMES FROM SEPTIC SYSTEMS1. THIS MEANS THAT OUT OF ALL THE NITROGEN THAT ENTERS THE CHESAPEAKE BAY FROM DIFFERENT SOURCES, ABOUT 6% COMES FROM THE WASTEWATER THAT IS RELEASED BY SEPTIC SYSTEMS. THIS IS A SIGNIFICANT AMOUNT, CONSIDERING THAT THERE ARE MANY OTHER SOURCES OF NITROGEN THAT CONTRIBUTE TO THE BAY’S POLLUTION.


Nurturing Your System


REMEMBER THESE GOLDEN RULES:


  1. REGULAR PUMPING: SCHEDULE TANK PUMPING EVERY 1 TO 3 YEARS TO REMOVE SLUDGE BUILDUP OR WHEN SLUDGE REACHES ABOUT 12 INCHES IN DEPTH
  2. MIND WATER USAGE: EXCESSIVE WATER CAN OVERWHELM THE SYSTEM.
  3. PROTECT THE DRAINFIELD: AVOID PARKING OR BUILDING STRUCTURES OVER IT.


Sources for Further Exploration


For deeper insights, consult these authoritative sources:



Your septic system—more than pipes and tanks—is a vital part of our ecosystem!

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