Unraveling the Septic System Jargon: 50 Key Terms Explained

Septic Tank Dude Author at Septic Tank Dude
Jack has been working all of his life in the septic tank maintenance, cleaning and pumping business. In 2020 when COVID hit he decided to retire from pumping septic tanks and use his knowledge to help out readers of Septic Tank Dude. Jack has a wealth of knowledge to share on septic tanks, leach fields and much more.
Jack Cacy

If you’re a homeowner with a septic system, you’ve likely come across terms that left you scratching your head. From ‘effluent’ to ‘leaching chambers,’ the language of septic systems can seem like a foreign tongue. That’s where we come in! In this enlightening guide, we decode 50 essential septic system terms to help you better understand and maintain your system. You’ll gain more than just vocabulary – you’ll discover the inner workings of your septic system, empowering you to detect issues early, make informed decisions, and keep your system running smoothly for years to come. Let’s dive into the fascinating world of septic systems!

don't wait for your septic to fail, prevent it


  1. Septic System: A septic system, or onsite sewage facility (OSSF), is a critical component of any household that isn’t connected to the municipal sewer system. It’s a self-contained, underground waste treatment system that turns wastewater into an acceptable effluent that is then dispersed back into the ground. A typical system consists of a septic tank and a drain field, or soil absorption field. Regular septic system maintenance is essential to prevent system failures and extend its lifespan.
  2. Septic Tank: A septic tank is an enclosed, watertight container that collects and provides primary treatment to wastewater by separating solids from the effluent. The tank allows for the separation of solid waste materials, enabling sludge to settle at the bottom and lighter waste, like oil and grease, to form a scum layer at the top. With time, anaerobic bacteria break down the solid waste in the tank. Understanding your septic tank size and how often it needs to be pumped is essential to ensure the system functions properly.
  3. household owner with septic tank treatmentLeach Field: The leach field, also known as a drain field, is an essential part of a septic system where the liquid effluent is further treated and dispersed into the soil. It is typically a series of trenches or a bed lined with gravel or sand and buried one to three feet below the ground surface. The leach field must be properly maintained to avoid system failure, including grass dying or turning yellow over the drain field.
  4. Distribution Box: A distribution box is a crucial component of the septic system, which receives effluent from the septic tank and evenly distributes it into the drain field lines. It ensures an equal flow of wastewater to all parts of the drain field, preventing overloading of a single line, which could lead to a system failure.
  5. Septic Drain Field: This term is often used interchangeably with the “leach field”. It is a critical part of the septic system where effluent is further treated and dispersed into the surrounding soil. Improper maintenance or overload can lead to a failing septic drain field, which can be costly to replace.
  6. Scum Layer: The scum layer in a septic tank is the accumulation of waste material that floats to the top of the tank. This layer typically consists of oil, grease, fats, and other light waste but can also get full of the wrong type of toilet paper. A too-thick scum layer can clog the septic system, leading to a need for a septic tank cleanout.
  7. Sludge Layer: The sludge layer in a septic tank is the accumulation of heavier waste material that sinks to the bottom of the tank. This layer is composed of inorganic solids and byproducts of bacterial digestion. If not properly maintained and pumped out periodically, the sludge layer can build up and eventually enter the drain field, causing system failure.
  8. Biomat: Biomat is a layer of biological material that forms at the soil interface in the drain field. It is composed of anaerobic bacteria, and it helps in the treatment process by filtering and breaking down organic material in the effluent. However, if the biomat becomes too thick, it can impede the flow of effluent into the soil, leading to system failure.
  9. Percolation Test:A successful percolation test is crucial before installing a new septic system to prevent potential drainage issues or system failures. If the results show the soil in your drain field is not suitable, you may need to consider a different type of septic system or a constructed wetland.
  10. Absorption Area: This is the portion of the leach field where the effluent is absorbed into the surrounding soil. The size and type of the absorption area depend on several factors, including the rate of percolation, the amount of wastewater generated, and local regulations. A well-functioning absorption area is vital for the overall health and functionality of a septic system. Understanding the absorption area is part of proper septic system maintenance.
  11. Septic Pump: A septic pump is a device used to move effluent from the septic tank to the drain field, especially when the system relies on a pump rather than gravity. Septic pumps can sometimes malfunction, which may lead to an alarm going off. If this happens, you should know what to do if your septic tank alarm is going off.
  12. Effluent: Effluent is the liquid waste or sewage that is treated in a septic tank and then discharged into the drain field. It’s crucial to maintain the balance of bacteria in your septic tank to ensure effective breakdown of solids and grease into effluent. There are certain products you can put in your septic tank to help break down solids and grease.
  13. Septic Filter: A septic filter, also known as an effluent filter, is installed at the outlet of a septic tank and it helps prevent solids from entering the drain field. The filter requires regular cleaning to ensure it functions optimally. You can learn more about how to clean your septic tank, including the filter, naturally here.
  14. sewer line clearing tabletsSeptic Additives: Septic additives are products that are added to a septic system with the intention of enhancing its operation or restoring the balance of the bacteria needed for the system to function effectively. Some believe that these additives boost the bacteria in the septic tank, but it’s always best to research and understand the truth about septic tank additives before using them.
  15. Inlet Baffle: The inlet baffle in a septic tank directs incoming wastewater downward below the scum layer. This design helps to prevent turbulence in the tank and allows the separation of solids and liquids to occur effectively. If the baffle is clogged or damaged, it can cause issues with your septic system.
  16. Outlet Baffle: The outlet baffle in a septic tank prevents the scum layer from exiting the tank and entering the drain field. If the outlet baffle is not functioning correctly, it could lead to system failure. It’s essential to check and maintain the outlet baffle as part of your septic system maintenance routine.
  17. Greywater: Greywater, often spelt graywater, refers to the relatively clean wastewater from baths, sinks, washing machines, and other kitchen appliances. Unlike blackwater, which is wastewater from toilets, greywater may be recycled for certain uses, such as irrigation and toilet flushing. It’s important to remember, however, that even if you’re using greywater, you still need to ensure your septic system, including the septic tank, is properly maintained. If not properly managed, greywater can still lead to septic system failures.
  18. Blackwater: Blackwater refers to wastewater that contains fecal matter and urine. It originates from toilets and is generally considered to be a health risk due to the pathogens it contains. Proper treatment of blackwater is crucial to prevent the spread of diseases, and it’s one of the primary functions of your septic system.
  1. Tank Cover: The septic tank cover, also referred to as a lid, is an essential part of the septic system. It provides access to the tank for maintenance and inspection purposes. It’s also vital for safety, preventing accidental falls into the tank. If you’re interested in aesthetically pleasing ways to conceal your septic tank cover, check out these creative ideas on how to hide septic tank cover.
  2. Tank Lid: Similar to the tank cover, the tank lid offers access to the septic system for routine maintenance and inspection. Knowing how to locate your septic tank lid is crucial. This step-by-step guide on how to find your septic tank lid easily provides valuable information.
  3. Onsite Wastewater Treatment System (OWTS): An OWTS is a system that treats wastewater on the property where it is generated. This includes septic systems, which are a type of OWTS. If you’re curious about septic systems as a wastewater treatment option, you may find this comparison of septic tanks vs. sewer vs. cesspool helpful.
  4. Onsite Sewage Facility (OSSF): Similar to an OWTS, an OSSF treats sewage on the property where it is generated. It typically includes a septic tank and a drain field. For those interested in learning more about septic systems, this septic system guide provides a wealth of information.
  1. Cesspool: A cesspool is an antiquated type of wastewater system. Unlike a septic tank that separates and processes waste, a cesspool merely serves as a catchment for sewage, letting it slowly percolate into the surrounding soil. Though less common today due to its environmental implications, it’s still found in older properties. To gain more insights about penalties related to illegal septic systems, which can include improperly used cesspools, refer to this blog post discussing the penalty for illegal septic systems.
  2. Septage: Septage is the scum, sludge, and liquid in septic tanks that needs to be regularly pumped out to keep the system functioning properly. Septage can pose a significant environmental hazard if not managed correctly. This post provides a comprehensive guide on how often a septic tank should be pumped.
  3. Risers: In the context of septic systems, risers are pipe sections that extend from the top of the septic tank to the ground’s surface. They provide easy access to the tank for maintenance and pumping. For more information on the benefits and installation of septic tank risers, refer to this guide.
  4. Septic Alarm: A septic alarm alerts homeowners to potential issues with their septic system, such as high water levels in the tank. If your septic alarm is going off, it’s crucial to understand the possible reasons and how to troubleshoot it. For more information on what to do when your septic alarm is sounding, read this helpful article.
  5. Nitrogen Reduction: Nitrogen reduction is a crucial process within a septic system, whereby bacteria in the system convert harmful nitrogen compounds into less harmful substances. Understanding the role of bacteria in your septic system can help ensure its proper functioning. You might find this article on boosting bacteria in your septic tank enlightening.
  6. Soil Absorption System: Also known as a leach field or drain field, a soil absorption system is where wastewater from the septic tank is dispersed into the soil for further treatment. When a septic system is functioning correctly, the drain field allows liquid to flow from the tank and be absorbed into the ground. For more insights into why grass might be dying or turning yellow over the drain field, refer to this post on why is my grass dying or turning yellow over my drain field.
  7. Gravity System: A gravity septic system uses natural downward force to move wastewater from the home into the septic tank and then out to the drain field. It’s one of the simplest and most common types of septic systems. For more information on different types of septic systems, visit this comprehensive septic system guide.
  1. Pressure Distribution System: Unlike a gravity system, a pressure distribution septic system uses a pump to distribute wastewater evenly throughout the drain field. This type of system is often used when the soil conditions are less than ideal for a gravity system.
  2. Mound System: A mound septic system is a type of septic system used when standard drain fields are not suitable. The system utilizes an elevated mound of sand and gravel through which wastewater is treated and dispersed. For more on mound systems, read this informative piece on understanding mound septic systems.
  3. Aerobic Treatment Unit (ATU): An ATU is a small-scale sewage treatment system that uses aerobic bacteria to break down waste, similar to a municipal sewage system. It’s often used when a standard septic system is not suitable. For more information on ATUs, check out this page about Aerobic Treatment Units: A solution for difficult sites.
  4. Soil Testing: Soil testing is an essential step in installing a new septic system. It determines the type of soil, its percolation rate, and its ability to treat and absorb wastewater.
  5. Drainage Patterns: Drainage patterns refer to how water moves across a landscape, which can significantly impact the functioning of a septic system.
  6. Trenches: Trenches, in the context of septic systems, are long narrow ditches in the drain field where perforated pipes are laid. The wastewater is released into these trenches and then absorbed into the surrounding soil. If you’re experiencing issues with your trenches, this guide on how to deal with a backed-up septic system may be helpful.
  7. Sand Filter System: A sand filter system is a type of septic system that uses a bed of sand to filter and treat wastewater before it’s dispersed into the drain field.
  8. Lateral Lines: Lateral lines are the pipes in the drain field that distribute wastewater from the septic tank into the soil. Understanding how your lateral lines function is key to maintaining a healthy septic system. This post on septic system maintenance offers useful advice.
  9. Inspection Ports:Inspection ports are openings in the septic system that allow for examination of the system’s interior without digging. They can provide early warning signs of system failure.
  10. Sewer Gas: Sewer gas is a byproduct of the decomposition of organic material in a septic system. It can include various harmful gases, including methane and hydrogen sulfide. If you’re noticing a sewer gas smell in your home, this article on how to get rid of septic smell outside is a gold mine!
  11. Soil Permeability: Soil permeability refers to the soil’s ability to absorb water, which is crucial for a functioning septic system. Soil with poor permeability can lead to system failure. This guide on elaborates on the significance of soil properties for septic systems.
  12. Septic Shock: Not to be confused with the medical condition, septic shock in the context of septic systems refers to the severe disruption of the system’s function, often due to factors like excessive waste or chemical introduction.
  13. Dosing Chamber: A dosing chamber, also known as a pump chamber, stores effluent coming from the septic tank before it’s pumped into the drain field. Understanding the different components of your septic system, including the dosing chamber, can help you maintain it effectively. This is where a septic tank treatment or best additive for septic tank should be delivered.
  14. Holding Tank: A holding tank stores wastewater and needs to be pumped out regularly because it doesn’t treat or discharge the waste like a septic system does.
  15. Septic System Maintenance: Regular maintenance is crucial to keep a septic system functioning properly and to extend its lifespan. For advice on how to maintain your septic system, refer to this comprehensive guide on septic system maintenance.
  16. Septic System Installation: The installation of a septic system is a complex process that requires careful planning and professional expertise.
  17. Leaching Chambers: Leaching chambers are plastic chambers used in the drain field to distribute wastewater into the surrounding soil. They are an alternative to traditional pipe and stone systems.
  18. Conventional System: A conventional septic system consists of a septic tank and a drain field or soil absorption field. It’s the most common type of septic system and is suitable for many residential and commercial properties. For more information on conventional septic systems and their maintenance, refer to this page on conventional septic systems.
  19. Advanced Treatment Systems: Advanced treatment systems, also known as secondary treatment systems, provide an additional level of treatment beyond what conventional septic systems offer. These systems can remove more pollutants, making them suitable for properties where standard systems are not adequate.
  20. Effluent Screen: An effluent screen is installed in the septic tank’s outlet to prevent solids from entering the drain field, which can cause clogging and system failure.
  21. Septic System Regulations: Septic system regulations can vary by location but typically cover aspects like system design, installation, maintenance, and inspection. Non-compliance can lead to penalties. To understand more about septic system regulations and compliance, refer to this post on the legal maze: what is the penalty for illegal septic system.
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