What is A Septic Tank & How Does it Work?

Septic tanks are crucial additions to thousands of properties in the UK, responsible for efficiently and effectively managing wastewater. If you’ve ever wondered about the inner workings of a septic tank, we aim to provide you with the insight that you require. In this article, we’ll explain what a septic system is and how it works, giving you the information needed to either well maintain your system or just increase your knowledge of the tanks. 

Septic tanks receive wastewater from the property, where solid waste settles at the tank’s bottom and oil and grease float to the surface. To prevent these substances from reaching the drain field, a T-pipe connection allows only the water to flow onward, where it undergoes treatment by natural bacteria in the drain field.

Septic tanks can seem like they are in-depth systems, however, once you know the basics of them, they are very easy to understand. In this article, we aim to provide you with all the knowledge you would need about how septic tanks work. 

What is A Septic Tank?

Septic tanks, though often overlooked, serve as crucial components of wastewater management for countless homes and businesses. At its core, a septic tank is a large, underground container designed to handle and treat wastewater from various sources within a property, effectively replacing the need for a centralised sewer system in more rural or less densely populated areas.

Understanding the primary purpose of a septic tank is essential for homeowners and property owners, shedding light on the vital role these systems play in maintaining clean and sustainable living environments.

How Does A Septic Tank Work?

Septic tanks are crucial for the disposal of wastewater. But how do they work, exactly? Inside this tank, heavier stuff like solid waste settles down at the bottom, while lighter things like oil and grease float to the top. To make sure only the water moves on, there’s a T-pipe that diverts it to a place called the drain field. This drain field is where nature steps in – natural bacteria in the soil break down and clean the water before it goes back into the environment. 

The Step-By-Step Process of A Septic Tank

Septic tanks have a clear and simple process that has been perfected since 1860, and it has only become more efficient over time. Here is the process:

  1. Wastewater Collection: The first step in the septic tank process begins inside your home or building. All wastewater from sinks, toilets, showers, and other appliances is channeled into the septic tank through a network of pipes. This raw wastewater contains everything from organic matter to soap residue and pathogens.
  1. Separation & Treatment: Upon entering the septic tank, the force of gravity initiates a crucial process. Solid particles, commonly known as “sludge,” settle at the tank’s bottom, while lighter substances like oils and grease form a surface layer called “scum.” In the space between these layers resides the relatively clear water known as “effluent.” The septic tank’s structural design effectively ensures that neither the sludge nor the scum can escape into the drain field, safeguarding the integrity of the wastewater treatment system.
  1. Effluent Disposal: The final step involves the treated effluent exiting the septic tank and flowing into the drain field or leach field via a t-pipe. Here, natural processes take over. Beneficial bacteria in the soil break down and further treat the effluent as it gradually sinks through the ground. This natural purification process ensures that the water returned to the environment is clean and safe, protecting groundwater and minimising environmental impact.

Does A Septic Tank Need Emptying Manually?

Proper maintenance of your septic tank is crucial to ensure its efficient and long-term operation. While septic tanks are designed to hold and treat wastewater, they are not limitless in capacity. Over time, solid waste and scum layers accumulate, reducing the available space for effluent treatment. Consequently, regular septic tank emptying and cleaning become necessary to prevent overflows, backups, and system failures. The frequency of septic tank pumping depends on factors such as tank size, household usage, and local regulations. Ignoring this essential maintenance task can lead to costly repairs and environmental issues, making septic tank maintenance a crucial aspect of responsible homeownership. Therefore, it is crucial to ensure your septic tank doesn’t become full.


How often should I have my septic tank pumped?

The frequency of pumping depends on factors like tank size and household usage. On average, it’s recommended to pump your septic tank every 3 to 5 years.

What can and cannot be flushed into a septic system?

You should only flush human waste and toilet paper into your septic system. Avoid flushing non-biodegradable items like wipes, hygiene products, and chemicals.

Are there any maintenance tips for a septic system?

Maintain your septic system by avoiding excessive water use, regular inspections, and pumping as needed. Use septic-safe products and avoid pouring chemicals down drains.