Septic systems transport wastewater from homes to a septic tank, where solids settle to the bottom, and microbes decompose them. The liquid wastewater, known as effluent, exits the septic tank through perforated pipes into a drain field (also called a leach field) of gravel and soil, filtering down to groundwater.
Nutrient Removal
Most septic systems use natural and technological processes to treat wastewater, from solid particles settling in the septic tank to nutrient removal in drain fields. However, it is essential to understand the limitations of these treatment systems, particularly in areas with sandy soils and shallow groundwater tables.
Insufficient renovation in a drain field can lead to nutrient transport from the septic system into shallow groundwater, contributing to eutrophication in nearby aquatic communities. To address this issue, the performance of two conventional drain field designs was investigated—drip dispersal and gravel trench—in a sandy soil environment.
Results from this study suggest that the type of drain field material is crucial to nutrient removal in a septic system. Research has also shown that the best vegetation for a drain field is shallow-rooted turf grasses, which minimize soil erosion and are adapted to frequent mowing. This ensures that the vegetation can “grab” and retain water, reducing abrasion and minimizing nutrient loss to the soil surface.
Soil Filtration
Soil acts as nature’s most significant natural water filter, an essential part of the new septic tanks system’s ability to purify wastewater. This filtration removes most bacteria, viruses, and some nutrients in the wastewater. However, pathogens and other soluble contaminants (meaning they dissolve in water) can move with soil water and sometimes end up in groundwater supplies.
This is why avoiding putting medicines, cleaning products, or other organic chemicals down the drain or toilet is essential. When the absorption field soils become saturated, they can no longer adequately filter wastewater.
This can cause sewage to go back into the house, putting you and your family at risk of direct contact with these harmful pathogens. This problem can be solved by properly maintaining the drain field and following a solid carpet cleaning protocol. These soils can be challenging to clean and usually require a strong oxidizer or solvent.
Biological Activity
The natural filtration of your septic system occurs in your drain field, where the soil acts as a biological filter by absorbing and breaking down harmful pathogens. This is made possible by a host of beneficial microorganisms within the soil. The health of this ecosystem is critical to your septic system and the environment around it, so it’s essential to keep these microorganisms healthy with regular maintenance.
This requires preventing the introduction of substances that harm these beneficial organisms. This includes avoiding harsh cleaners, excessive use of household chemicals, and putting down paving or other long-term weight loads over your drain field.
Groundwater Protection
The natural process of the movement of water through the soil and rocks, absorbing and dispersing chemicals, converting organic waste into usable nutrients, and slowing groundwater’s movement. Geologic materials, human activities, and the biological activity of microorganisms influence the process.
A septic system’s function is to create a controlled environment where bacteria, worms, and other living things break down the waste that goes into it. Then, the liquid moves to a drain field that completes the treatment by consuming any remaining nitrates and other contaminants. It’s essential to protect our groundwater supply.
Most public drinking water systems get all or part of their supplies from underground aquifers. If you get your water from a private well, it’s essential to be a good steward of your well and the groundwater it depends upon. Don’t pour anything down the drain or on the ground that could pollute your water; take used motor oil and medications to a hazardous waste collection facility.