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  • Writer's pictureRob Byrne

Septic Tanks vs Cesspools

Septic systems and cesspools are both types of onsite wastewater treatment systems commonly used in residential and commercial properties where there is no access to a centralized sewer system. While they serve a similar purpose of managing and treating wastewater, there are significant differences between septic systems and cesspools in terms of design, function, and environmental impact.

  1. Design and Structure:

    • Septic System: A septic system consists of a septic tank and a drainfield. The septic tank is a watertight underground container made of concrete, fiberglass, or polyethylene, which collects and separates solids and liquids in the wastewater. The clarified liquid, known as effluent, is then discharged into the drainfield for further treatment and absorption into the soil.

    • Cesspool: A cesspool, also known as a cesspit or a soakaway pit, is a simple underground pit or cavity dug into the ground. It does not have the same separation of solids and liquids as a septic tank. Wastewater enters the cesspool directly, and the solids settle at the bottom, while the liquids leach into the surrounding soil.

  2. Function:

    • Septic System: In a septic system, the septic tank performs the primary treatment by allowing solids to settle and form a layer of sludge at the bottom, while fats and oils float to the top to form a scum layer. The partially treated effluent flows into the drainfield, where it is further treated and absorbed into the soil through a network of perforated pipes.

    • Cesspool: Cesspools rely mainly on the surrounding soil for filtration and treatment of wastewater. As the wastewater seeps into the soil from the cesspool, it undergoes natural biological and physical processes to break down harmful bacteria and remove pollutants. However, cesspools provide limited treatment compared to septic systems.

  3. Environmental Impact:

    • Septic System: Properly functioning septic systems can effectively treat wastewater and minimize environmental impact. The soil in the drainfield acts as a natural filter, removing harmful bacteria, viruses, and nutrients from the effluent. However, if a septic system is not properly maintained or overloaded, it can lead to groundwater contamination and pose risks to public health and the environment.

    • Cesspool: Cesspools have a higher risk of pollution because they lack the separation and treatment mechanisms found in septic tanks. The direct discharge of untreated wastewater into the surrounding soil increases the chances of groundwater contamination and surface water pollution. As a result, many jurisdictions have prohibited or phased out the use of cesspools due to their environmental concerns.

  4. Maintenance and Lifespan:

    • Septic System: Septic systems require regular maintenance, including periodic pumping of the septic tank to remove accumulated solids. It is also essential to avoid disposing of harmful substances like chemicals and non-biodegradable items into the system. With proper care and maintenance, septic systems can last for several decades.

    • Cesspool: Cesspools generally require less maintenance compared to septic systems since they lack mechanical components. However, regular inspection and pumping may still be necessary to prevent overflow and ensure proper functioning. The lifespan of a cesspool is typically shorter than that of a septic system.

Overall, septic systems are considered more advanced and environmentally friendly compared to cesspools. They provide better wastewater treatment, reduce the risk of pollution, and are often the preferred option where local regulations permit. If you have specific questions or concerns about septic systems or cesspools, it is advisable to consult local regulations and professionals who specialize in wastewater treatment systems for accurate guidance

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