While a majority of households in the United States are connected to the municipal or public sewers, a significant number of properties still rely on a private septic system. This accounts to almost 25% households that disposes wastewater through unsewered or onsitesystems.
This means that these home owners are accountable for treating and maintaining the wastewater disposal. The most popular technique in use is a septic system, a mechanism that use soil to treat small flows of wastewater.
All home or office facilities such as toilets, dishwashers, bath tubs, and sinks; which result in sewage need to be connected to a sewage system. However, roof drains, footing drains, water softening waste, and storm water pipes are not supposed to be connected to a sewage system.
Most homes having a septic tank also use private wells to utilize ground water as potable water. Septic tank systems usually depend on groundwater to remove toxic bacteria and that processed waste water tend to be a part of the ground water system again for drinking purpose. As a result, a safe and reliable septic system design is critical.
A septic system refers to a subterranean wastewater treatment structure, which is widely used in areas where there are no centralized sewer systems. It implements a blend of nature and a proven technology for processing the wastewater coming from the household plumbing system.
A standard septic system features a drain or a soil absorption field and a septic tank. The tank absorbs the organic matter and splits the solids and floatable matter such as oils from the wastewater.
A soil-based system emits the liquid or effluent from the tank into a sequence of perforated pipes existing in a leach field or some special unit that gradually release the effluent into the surface water or soil. Alternatively, gravity or pumps are used to emit the effluent via sand in the form of trickle.
Other than sand, even a wetland or organic matter such as sawdust or peat is used to remove or neutralize pollutants such as phosphorus, nitrogen and disease-causing pathogens. A few alternative systems work by evaporating wastewater or sterilizing it before it reaches the surface water or soil.
In short, a septic system is a self-reliant, highly efficientwastewater treatment technique. As it disposes household wastewater on the site, say in the householder’s backyard; the septic tank is inexpensive than a centralized sewer system.
The overall design is also simple, which makes it easy to install and maintain such a system. Further, due to the natural processes in use, it does not require sewer lines. As a result, a septic system is less troublesome for the environment.
All household wastewater leaves the home via a sewer pipe that is connected to a septic tank. This tank is a watertight buried vessel made up of typically concrete or fiberglass and featuring an inlet and outlet pipe. The tank holds the wastewater until all solids and liquids separate completely.
This natural process results in three layers within the tank. Solids that are lighter than water, such as oils or greases, float on the top and forms a scum layer. Solids that are heavier than water settle down at the bottom, forming the sludge layer. The middle layer is of the partially clarified wastewater.
Solid materials start to decompose, while the anaerobic breakdown of bacteria occurs. The sludge and scum layers continue to be in the tank, while the naturally available bacteria in the wastewater break down the solids. The sludge and scum that do not break down remain in the tank, until it is pumped or emptied.
The clarified liquid (effluent)then flows to the drainfield, also known as the soil absorption system, leach field, or a drain field. At times, a distribution device is there to distribute the wastewater uniformly in the drainfield.
This field is a collection of a channel or a bed lined with course sand or gravel. It is placed one to three feet under the ground and has perforated pipes running through it for distributing the wastewater. The field allows the water to trickle from the pipes gradually into the gravel and beneath the soil.
Here, the soil and gravel work as biological filters.Compartments and outlet vest or a baffle in the tank do not allow the scum and sludge to leave the tank and penetrate into the drain field. The tank should be pumped at an interval of 3-5 years for removing the two layers.
If the drainfield is overflowing, it will flood and keep wastewater treatment at bay. As a result, the sewage water flows back up into the house. To prevent this issue, it is ideal to have a reserve drainfield as a new drainfield.
The size of the field is dependent on how well the water is absorbed by the ground. If the ground is of hard clay, the field needs to be much bigger, as the water absorption rate is slow.
The waste water in the drainfield percolates into the soil for filtration. Natural processes in use tend to throw a majority of pollutants from the wastewater before it mixes with the groundwater. Aerobic bacteria breakdown is also a part of the process.
A septic system is usually powered by gravity. In a nutshell, water flows down to the tank and then to the field from the house. It is a fully passive system.
The EnvironmentalProtection Agency in the United States has developed consents to regulate the installation and working of septic tanks for guiding the local communities in terms of protecting health and improving water quality.
A few protected areas are likely to benefit from regulatory programs, as they cover site assessments to find out how porous is the soil and whether the groundwater shall be threatened or not.