Most Americans connect their home plumbing to their municipal sewage treatment plant, but roughly 25% of them use septic systems. These underground wastewater treatment structures filter household waste, pumping clean water back into the environment. In the video above, plumbing and heating expert Richard Trethewey demonstrates the inner workings of a septic system using a cutaway model, showing the entire septic filtration process.
Read on to see how septic systems work, what their components are, and how to maintain your septic tank to keep it running smoothly. Also, check out our comprehensive septic tank guide for homeowners to get a crash course in waste management.
Components of a Septic System
A typical septic system has several key components to help process household waste efficiently. The following three components are the building blocks of any successful septic system.
The Septic Tank
The septic tank is the heart of the whole septic system. It’s usually made of concrete or fiberglass and can hold over 1,000 gallons of waste. It acts as the first stage of treatment, where solid waste separates from liquid waste.
Distribution Box
This component diverts wastewater from the septic tank and evenly distributes it to the leach field pipes. Not all septic systems have a distribution box, but most do.
Leach Field
The leach field is a network of perforated pipes laid in gravel-filled trenches. It’s designed to filter wastewater and return it to the earth. This is the last component wastewater passes through before it leaves the septic system.
How Septic Systems Work
When wastewater leaves your home, it travels through a main drainpipe into your septic tank. This waterwater includes water from toilets, sinks, showers, and appliances. Once it reaches the septic tank, it starts its filtration process.
The Septic Tank Filtration Process
A typical septic tank consists of two chambers divided by a half-wall. As waste enters the tank, it undergoes a natural separation process:
- Solid waste settles to the bottom of the first chamber, forming a layer of sludge.
- Lighter materials, such as grease and oils, float to the top, creating a scum layer.
- The clearer liquid in between, called effluent, flows over the dividing wall into the second chamber.
In the tank, anaerobic bacteria break down the solid waste, converting much of it into liquid form. This process is continuous, allowing the system to handle ongoing waste input from the household.
Leach Field Filtration
After treatment in the septic tank, the effluent flows out into a series of perforated pipes in the leach field. The leach field is where the septic system releases filtered wastewater back into the earth, making room for more wastewater to accumulate in the septic tank.
These pipes typically flow into gravel or stone, which helps to distribute the liquid evenly into the soil. Beneficial bacteria in the soil continue to break down any remaining contaminants, purifying the water before it rejoins the groundwater table.
Advanced Septic Systems
Most homes have traditional septic systems, but there are also some advanced systems that offer solutions for challenging environments or higher treatment standards. These include:
- Aerobic treatment units (ATUs): These units introduce air into the treatment process, enhancing bacterial activity and breaking down waste more efficiently.
- Sand filters: This adds a layer of sand to help filter out impurities from effluent before they reach the leach field.
- Drip irrigation systems: These systems distribute effluent through small, flexible tubing, making it suitable for shallow or rocky soils.
If you live in an area with poor soil quality, high water tables, or where environmental regulations require additional treatment, you may need one of these advanced septic systems. Be sure to talk to a professional plumber before deciding on the system that’s best for your home.
Maintaining Your Septic System
Cleaning and pumping your septic tank is a messy business, so it helps to maintain your septic system to avoid any unnecessary complications.
Regular Pumping
Even with proper use, septic tanks need periodic pumping to remove accumulated solids. The frequency depends on factors such as:
- Amount of solids in wastewater
- Household size
- Tank size
- Water usage
Most tanks require pumping every three to five years, but it’s best to talk with a septic professional to learn about the cost of pumping a septic tank and to set up a personalized pumping schedule.
What Not to Flush
To keep your septic system healthy, be mindful of what goes down your drains. Avoid flushing or pouring:
- Baby wipes
- Coffee grounds
- Dental floss
- Grease and oils
- Kitty litter
- Paint or chemicals
- Sanitary products
These items can disrupt the bacterial balance in your tank or clog the system, leading to backups. At best, they still contribute to the scum layer in your tank, so you should avoid flushing these items. For more on septic safety, check out the United States Environmental Protection Agency’s guide on protecting your pipes.
Signs of Septic System Problems
Since your septic tank is underground, it can be easy to miss the early signs of a septic problem. If you want to stay on top of septic issues as soon as they come up, keep an eye out for:
- Bad odors around the drain field
- Gurgling sounds in the plumbing
- Sewage backing up into the house
- Slow-draining sinks or toilets
- Wet or spongy ground near the septic system
If you notice any of these signs, contact a septic professional immediately for an inspection.
Common Causes of Septic Failures
Septic system failures are not uncommon, and while they’re unpleasant to deal with, you can prevent them if you know the causes and how to avoid them. Some typical causes include the following:
- Excessive water usage: Overloading the system with too much water can prevent adequate waste treatment.
- Improper disposal: Flushing nonbiodegradable items can clog pipes and disrupt the bacterial balance.
- Tree root intrusion: Roots from nearby trees can invade and damage the system’s components.
If you suspect any of these issues, reach out to a septic professional immediately. Addressing these causes as soon as they come up can help prevent any major problems.
Septic System Additives: Helpful or Harmful?
In the video above, Richard Trethewey suggests that enzyme-based additives can be helpful in maintaining a healthy bacterial balance in your tank. However, he cautions against overuse, as too much of any additive can disrupt the natural processes in the tank.
If you choose to use additives, you need to:
- Follow the manufacturer’s instructions carefully
- Avoid additives with any harsh chemicals
- Select products specifically designed for septic systems
- Use them sparingly as a preventative measure rather than a cure for existing problems
Remember, no additive can replace proper maintenance and regular pumping of your septic system. Many additives, especially ones with harsh chemicals, can even be harmful to your plumbing. When in doubt, trust in your septic tank’s natural process for breaking down organic waste and do your best to maintain it using the tips in this article.