How Does A Septic Tank Work And Other Vital Questions

Have you ever asked yourself how does a septic tank work? Before you learn how a septic tank works, there are a few things you should know. A septic tank provides wastewater treatment for your home. The tanks are common in rural homes because they aren’t connected to a central sewage system.

According to the Environmental Protection Agency (EPA), “More than one in five households in the United States depend on individual onsite or small community cluster systems (septic systems) to treat their wastewater.”  

Septic Tank

If you have a septic system, you should know how to take care of it so it will last longer.  Should you fail to provide proper care for your sewage waste system, serious problems will arise.

What Is A Septic Tank?

A septic tank is an underground chamber made of a solid material through which wastewater flows and is disposed of. It is a domestic wastewater disposal system.

Septic tanks do not operate by themselves. The tanks are connected to septic network. A new septic tank is cheaper than connecting to your city sewage system.

How Does A Septic Tank Work?

How Does A Septic Tank Work

Septic tank sewage is decomposed by bacteria, making it easier to transfer. Decomposed matter it known as “sludge,” which settles at the bottom of a tank. Waste that doesn’t decompose floats to the surface, which is called “scum.” Scum and sludge have a water layer between them. 

Septic tanks reduce the movement of raw sewage and waste. Without a septic tank, sewage would enter the surrounding soil. This is bad for the environment and human health.

Absorption Field

Excess water flows into the absorption field after passing through the septic tank. The soil needs to be percolated and then becomes solid and packed like clay. 

Loose soil like sand isn’t good because water can’t pass through it nor will it be absorbed. This is where the absorbtion field comes in. Another name for the absorption field is the drain field.

Septic Tank Diagram And Parts

Septic Tank Diagram And Parts

Now, let’s take a look at the septic system and the parts that make up a septic tank. Because learning each part of the septic tank can help you learn how to care for your septic tank and give your system the longest life possible. 

Input Baffle

The input baffle is where the sewage enters from the house. This pipe is connected to your plumbing. Anything that drains outside is usually connected to this input baffle pipe. This can also be called the inlet baffle. 

This is usually made of a pipe that matches the pipe connected to the house. This pipe is hidden and can only be accessed by a professional. A blueprint of septic pipes should be kept on hand if possible. 

Output Baffle

The outlet baffle is the area and pipe where the wastewater goes to the drain field or absorption field. This is how the wastewater escapes and how the septic tank doesn’t overflow. Though a low capacity tank may struggle even with this output.

The output pipe contains a filter to ensure nothing escapes the septic tank that isn’t cleaned first. If contaminated water enters the drain field, it could cause a hazardous domino effect. 

Scum Layer

The scum layer is made up of the non-decomposed matter that floats to the top. Gasses that the sludge layer creates will also float to the top. This is called the “scum layer.” It is visible from the inspection pipes.

Septic tank wastewater partially filters the scum layer. It’s skimmed during inspection and pumped out with the sludge layer and wastewater.

Sludge Layer

The sludge layer is made up of decomposed matter that goes through the sewage system and enters the septic system. This sludge is cleaned and pumped, settling on the bottom while evaporating. 

Yes, the name sludge layer is quite stomach-turning, but it is an accurate description. Removing the sludge layer is important when the septic tank is pumped out every few years. 

Inspection Pipe

The inspection pipes allow professionals, or you, to view the levels of the water and scum in the septic tank. You can lift the lid and view it at any time which will let you know when you need to pump the tank.

The inspection pipe is only a few inches wide and has little use except to view the septic tank without having to dig it up. Digging it up may need to be done if the manhole is buried without a large pipe attached. 

Manhole Cover

The manhole cover is large enough for someone to fit into. However, it should not be used except by a professional to inspect the tank or to pump it out. That is the use of the manhole cover, so try to leave it alone. 

The only thing you need to check for if the manhole is visible is leaks. Leaks could indicate that the manhole isn’t secure well or that the septic tank is overfilled. Both are problems that need to be addressed. 


The wastewater level is the water that is passed through the plumbing system. This is the water that will enter the wastewater drain field. It has been filtered and will be safe for draining into the field. 

Flushed toilet water is wastewater. The wastewater will disperse into the ground but overfilling the tank will disrupt the process. Your septic tank should be large enough to hold wastewater.

Septic Tank Safety Tips

Septic Tank Safety Tips

Septic tanks are a health hazard when neglected. Make it a priority to have a well maintained septic system. For best results, a professional should handle all matter related to your septic tank. The tank should be inspected annually.

Never Enter A Septic Tank

The manhole cover may be tempting if you want to inspect your tank, but it should never be used by you. So never enter your tank under any conditions. Professionals have special gear to protect themselves. 

Related: Septic Tank Treatment Options You Can Do Yourself

Don’t Place Under A Structure

When placing your septic tank, never install it under a deck, patio, or structure. It is important to maintain easy access. If you cover your septic tank, it will be difficult to pump or repair. 

Stay Above 1,000 Gallon Capacity 

A tank with less than 1,000 gallons of capacity is dangerous. Use the 1,000 gallon minimum unless a professional tells you to use less. If you have more than three bedrooms, you’ll need a bigger one.  

Pump Your Septic Tank Every Three Years

Your tank should be inspected every two or three years. You will need to pump your tank every four years. Your septic tank professional will let you know when it’s time to pump the tank it during his yearly inspection. 

Don’t Let Food In

Only waste should go in the septic tank. Avoid using garbage disposals if the sink drain is set to enter the septic tank. Oils, food, or foreign objects should not enter the tank unless the tank is designed to handle such items.

Conserve Water

Don’t use more water than necessary. Running water or taking long showers will require you to pump your septic tank every two years or more. Conserving water will reduce the need to pump your septic tank.

Watch For Groundwater Contamination

This is an important thing to do. Ask the team that inspects your septic tank to check the water around the drain field. If it is contaminated, then the filter isn’t working properly and could become a health issue. 

Frequently Asked Questions (FAQ)FAQ

Should I Install A Septic Tank?

If you have neighbors, ask them about a septic tank. Your neighbors are on the same septic system. If you live alone in a rural area, your local septic contractors can help you. 

How Much Does A Septic Tank Cost?

If you want to hire a professional to install your septic tank, you’ll spend between $3,500 to $9,000. Unless you have experience, do not install a septic tank alone. Septic tank installation is not a DIY project. 

Why Is Sodium Laureth Sulfate Bad For Septic Systems?

Sodium Laureth Sulfate (SLS) is a foaming chemical. It can cause permanent damage to your septic tank. SLS can also lead to health problems. If you want to clean your septic tank, use vinegar.

How Is The Empirical Assessment Model Applied To Septic Tanks?

Empirical assessment includes percolation rate, septic tank density, septic tank age, wastewater flow, depth to groundwater, distance to nearest water well, and relationship to well.

What Are The Two Parameters Concerning Septic Tank System Behavior?

The amount and concentration of recharge reaching the groundwater. Both of these parameters need to be calculated using estimates for input data.

How Is The Size Of A Septic Tank Determined?

Home septic tank size hinges on how many bedrooms the house has. A septic tank removes 75 percent of solids, oil, grease, and raw sewage.

How Does A Septic Tank Work Conclusion

Septic tanks work by safeguarding against harmful coliform bacteria. Untreated waste is harmful to your health. Human waste and household waste, like toilet paper are bad for you and the environment. 

When you have a septic tank, it will only function properly if you take care of it. Regular pumping is necessary. Waste debris like food scraps, paper towels, and other solid matter will clog your septic tank. If you do not prevent clogging, then waste overflow will be an issue.