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What are the 3 Types of Septic Systems in the UK?

In the UK, particularly in areas far from municipal sewage treatment facilities, septic systems play a vital role in managing household wastewater.

These systems are designed to treat and dispose of domestic sewage in a safe and environmentally friendly manner. While there are various septic systems available, three main types are most commonly used in the UK: the Conventional Septic System, the Septic Tank with Soakaway Crates, and the Sewage Treatment Plant Systems.

This article delves into the details of each system, helping homeowners understand their options.

Conventional Septic System: The Traditional Choice

The conventional septic system, a long-standing solution in rural areas, comprises two primary components: a septic tank and a drainage field, also known as a leach field. In this system, household wastewater flows into the septic tank, where it separates into layers.

Solids settle at the bottom, forming sludge, while oils and grease float to the top, creating a layer of scum. The middle layer, consisting of partially clarified wastewater, then exits the tank and flows into the drainage field. Here, the soil performs a natural filtration process, removing harmful bacteria and nutrients from the water. This type of system is particularly suitable for properties with adequate space for a drainage field and where the soil has suitable water-absorbing properties.

Septic Tank with Soakaway Crates: Adapting to Soil Variability

Recognizing the challenges posed by less permeable soils, the septic tank with soakaway crate system offers an effective alternative. This system is similar to the conventional one but includes a soakaway crate system after the septic tank. These crates provide a larger surface area, facilitating the absorption of effluent into the ground, even in areas where soil conditions are not ideal for standard drainage fields.

This system is an innovative adaptation, enabling more properties to manage their wastewater effectively, even in challenging soil conditions.

Sewage Treatment Plant Systems: Advanced Wastewater Treatment

For properties seeking a more advanced level of wastewater treatment, sewage treatment plant systems are the solution. These systems go beyond merely separating the waste; they actively treat it using mechanical components.

The process involves aerating the wastewater, which encourages the growth of bacteria that digest pollutants. The resulting treated water is clean enough to be discharged directly into a drainage field or, in some cases, even into a watercourse, provided it complies with environmental regulations. These systems are particularly suited for environmentally sensitive locations or where regulations require a higher standard of wastewater treatment.


Understanding the different types of septic systems available in the UK is crucial for homeowners, particularly those in rural areas without access to central sewage systems. Each system has its unique features and is suited to specific circumstances, such as the property’s location, soil type, and environmental considerations. Regardless of the type, regular maintenance and adherence to regulations are essential for the effective and sustainable operation of these septic systems.

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