What is an On-Site Wastewater Treatment System?

An on-site wastewater treatment system, also known as a decentralised wastewater treatment system, is a type of wastewater treatment system that is located at or near the source of the wastewater. It is typically used in areas where a main sewer is not available or practical, such as rural areas, remote locations, or small communities.

On-site wastewater treatment systems are designed to treat the wastewater generated by individual homes, buildings, or small groups of homes or buildings. They can be used for both domestic and commercial projects. They can vary in complexity and performance and can include septic tanks, packaged secondary wastewater treatment systems, or tertiary wastewater treatment systems.

A septic tank is the most common type of on-site wastewater treatment system that consists of a wastewater tank that separates solid and liquid waste and a percolation area (drain field) where the liquid, or effluent, is further treated by natural processes such as filtration and bacteria digestion.

A packaged secondary wastewater treatment system is a pre-manufactured, compact, and self-contained treatment system that typically uses mechanical or biological methods such as aeration, filtration, and bacteria digestion, to treat wastewater to a higher level of treatment efficiency and effluent quality.

A tertiary wastewater treatment system is a more complex type of on-site wastewater treatment system, that uses a packaged secondary wastewater treatment system and a coconut filter, peat filter, or sand filter installed on a gravel bed to treat wastewater to the highest level of treatment efficiency and effluent quality. You would typically use tertiary wastewater treatment systems when you have poor ground conditions, limited space available, or your site is located in a sensitive area.

When you are installing a new on-site wastewater treatment system it is important to have an EPA Site Suitability Assessment carried out to determine which type of system is suitable for your site. Not only do you comply with the EPA Code of Practice 2021 and Local County Council regulations, but you also protect your investment by ensuring you won’t have any problems in the future.

In summary, on-site wastewater treatment systems are designed to treat the wastewater generated by individual homes, buildings, or small groups of homes or buildings, in areas where a main sewer is not available or practical. They vary in complexity and performance and can include septic tanks, packaged secondary wastewater treatment systems, or tertiary wastewater treatment systems.