What are the different types of septic systems?

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As a homeowner living in an area without a municipal sewer system, you are probably looking for alternative options. Septic systems are widely used, but different types require different maintenance levels, weather conditions, investment, land area, and soil. 

Today, we will discuss what are the different types of septic systems, particularly conventional and alternative septic systems. We will explain how they function, what they consist of and their advantages and disadvantages.

Septic system basics

A septic system contains a few different components depending on its specific type. It is used in residential and business areas where no municipal sewer system is present to treat local wastewater. All wastewater flows from the property to the septic system to be treated, purified and then released into the soil. 

Conventional septic systems

How do they work?

The conventional pump septic system is one of the most popular types of septic systems. They are not made for use by large groups of people and are mainly installed in small households and businesses. A septic tank and drain field comprise a decentralized wastewater treatment system. 

In a conventional septic system, the wastewater from the house flows into the septic tank, where solids are settled. The process then continues by the wastewater flowing into the drain field, where the soil filters it out and breaks it down. The treated water then absorbs into the underlying layers of soil and flows into the groundwaters.

Pros & Cons

A conventional system has the main advantage of inexpensive installation and maintenance. Unfortunately, installing such a system in specific soils, such as clay, rock, and shallow soils, is not recommended. The main reason for this is that it can cause an overflow and flooding in wet seasons because of the soil’s absorption qualities.

Alternative septic systems

Intermittent sand filter systems

How do they work?

Intermittent sand filter systems (or ISF systems) are an alternative type of septic system that involves sand or, in rare cases, bottom ash, mineral tailings and similar. The two main components of such a system are a pretreatment unit (e.g., septic tank) and a 24-inch deep sand filter. 

The system’s function depends on gravity and a proper downward flow. After the primary contaminants are removed inside the septic tank, the effluent continues its treatment process through the different levels of the sand filter system. The treated water is then discharged into the drain field by an underdrain or a pump discharge underdrain.

Pros & Cons

The ISF system’s benefits are the low energy requirements and the absence of chemical use. Maintenance and construction costs are relatively low, while the wastewater treatment efficiency is very high. A con can be considered the required land area and the possibility of unpleasant odors. There is a risk of filter clogging. 

Recirculating sand filter systems

How do they work?

Recirculating sand filter systems (or RSF systems) use sand filters to create physical, chemical and biological processes which lead to water purification. They consist of three main elements: a pretreatment unit, a recirculation tank and an open sand filter. 

Wastewater flows into the septic tank from the residency, where its primary contaminants are filtered out. The effluent then enters the recirculation tank, where it’s pumped towards the sand filter. After it passes through the sand, it is released into the drain field.

Pros & Cons

If you live near large water bodies or live on a site with high water tables, an RSF system would be a good solution. This system doesn’t require any chemicals and provides a high level of effluent treatment. A disadvantage is that they are more expensive than other types of septic systems and require periodic maintenance.

Mound septic systems

How do they work?

A mound system is another type of septic system. It consists of a septic tank, a pumping chamber and a mound (a specific kind of sand, forming a drain field raised above ground level). Wastewater from the house enters the septic tank, after which it’s transported to the pump chamber. tank

The pump’s function is to distribute the flow towards the mound in specific and regulated doses. The water is then additionally treated while it transfers from the sand through the levels of soil. 

Pros & Cons

Mound septic systems, unlike conventional ones, can be used and installed in shallow soils or soils with high groundwater. They are the perfect solution for people whose properties are located on such grounds. Keep in mind that you need substantial space for such an installation. In addition, you need to maintain the system regularly.

Aerobic septic systems or aerobic treatment units (ATUs)

How do they work?

An aerobic treatment unit (ATU) is a more mechanical septic system. Its function is to pump oxygen into a treatment tank that feeds aerobic bacteria. These bacteria serve to treat the effluent by breaking down harmful pathogens. 

An aerobic septic system consists of a few different elements, including:

  • Trash tank
  • Aerobic treatment unit
  • Disinfectant chamber
  • Pump tank
  • Absorption field

Pros & Cons

It’s recommended to use aerobic septic systems if you live in an area with inadequate soil conditions, such as high water tables, or if your residence lacks space. It’s also preferable to use such a system if you live near a contamination-sensitive water body. 

The downside is that these units are very mechanical and require electricity and more maintenance than other types of septic systems.

Low-pressure pipe septic systems

How do they work?

A low-pressure pipe septic system (or LPP) consists of a septic tank or an aerobic unit, a pumping or dosing chamber and distribution laterals (PVC pipes) with a small diameter and perforation holes. 

The wastewater first goes through a primary treatment in the septic tank, where all the solids are separated. After that, it flows into the pumping chamber, where it’s stored until it’s time to be dispersed throughout the pipes under low pressure and into the drain field. 

Pros & Cons

An LPP system installation allows using sloping grounds and placing the drain field upslope. It enhances aerobic bacteria growth and doesn’t require much land to install. Unfortunately, these systems are prone to clogging, so regular maintenance is needed.

Chamber Systems

How do they work?

Chamber systems are a type of gravel-less septic systems. Instead of using gravel for the drain field, new effluent-distribution methods were developed, including plastic chambers and geotextile-wrapped or polystyrene-wrapped pipes. 

The chamber gravel-less system consists of several connected chambers, and the surrounding area is filled with soil. It works by bringing wastewater to the chambers where it comes in contact with the soil, and bacteria start treating the effluent.

Pros & Cons

The main benefit of such systems is that you can use them if you own limited space, don’t have access to gravel or need easy delivery and construction. They are also suitable for areas with high groundwater tables. Another advantage is that they are made out of recycled materials and reduce carbon footprint.

Drip Distribution Systems

How do they work?

The drip distribution system is another type of septic system. It consists of a pretreatment device (advanced or a septic tank), a pump tank, a filtering device and a distribution system. 

This system works in the following way:

  • First, wastewater arrives at the pretreatment device, where the contaminants are removed.
  • Then, it flows into the pump tank, where it gets stored until it’s dosed.
  • A pump transfers the water from the pump tank to the filtering device.
  • The filters (sand, disc or spin) remove larger particles from the water that would eventually block the dripping system.
  • The water flows into the distribution system, which is made of underground tubes with flow regulators.
  • The flow regulators release the water into the drain field, dosing it by time or demand.

Pros & Cons

The main benefits of a drip distribution system are that you can use it in various drain field conditions, including shallow soil and steep slopes. It provides regulated moisture and nutrients for growing plants. On the downside, you need more area to install a large pump tank to store large quantities of water and a larger budget for electricity.