If you are unfamiliar with the concept, pretreated effluent is applied to soil through a series of tubes equipped with emitters that allow a small amount of effluent into the soil at a time. This allows the effluent to be distributed more evenly over a large area.
- Drip distribution pumps pretreated wastewater to a soiltreatment site where the wastewater provides nutri-ents and moisture for plants. The pretreated effluent“drips” out of tubing at regular intervals, allowing a smallamount of wastewater to irrigate a large vegetative area.Topsoil with vegetation is an excellent environmentbecause it maximizes the treatment of sewage and mini-mizes the risk of untreated water flowing quickly throughthe soil.
What is a pretreatment septic system?
Pretreatment components remove many of the contaminants from the wastewater to prepare the effluent for final treatment and dispersal into the environment. The level of treatment is selected to match the receiving environment and the intended use.
Why would you need a drip septic system?
A drip septic system releases small amounts or “drips” of wastewater at regular intervals, maximizing the treatment of sewage and minimizing the risk of untreated wastewater quickly flowing through the soil.
Should I use septic tank additives?
There is little scientific data to suggest that you should add bacteria or enzymes to your septic system. The United States Environmental Protection Agency reported that biological additives do not appear to improve the performance of healthy septic tanks.
How does drip septic system work?
In general, a drip irrigation system is nothing more than a type of pressure distribution system where the goal is to spread the septic tank effluent out over both space and time. This means that effluent is applied across the entire soil treatment area (space) and at certain times of the day (time).
Which are pretreatment units?
Primary types of pretreatment units include multimedia filtration, activated carbon units, and water softening units. Multimedia filtration removes particulate matter from raw water by passing raw water through inert material layers of anthracite and sand of decreasing particle size.
How do you tell if your septic tank is full?
How to tell your septic tank is full and needs emptying
- Pooling water.
- Slow drains.
- An overly healthy lawn.
- Sewer backup.
- Gurgling Pipes.
- Trouble Flushing.
How long does a drip septic system last?
The typical life expectancy of a septic system is 25 to 30 years.
What are the 3 types of septic systems?
Types of Septic Systems
- Septic Tank.
- Conventional System.
- Chamber System.
- Drip Distribution System.
- Aerobic Treatment Unit.
- Mound Systems.
- Recirculating Sand Filter System.
- Evapotranspiration System.
What to do after septic is pumped?
After you have had your septic tank pumped by a trusted septic company, there are some things you can and should do as the septic system owner.
- 1) Get on a Schedule.
- 2) Take Care of the System.
- 3) Know the Parts of Your System.
- 4) Check Other Possible Issues.
What is the best thing to put in your septic tank?
Biological Additives. Biological additives, like bacteria and extracellular enzymes, are the only acceptable septic tank treatment for promoting a healthy, natural bacterial ecosystem, maintaining an effective drain field, and protecting the health of the local groundwater.
How do I add good bacteria to my septic tank?
Flush a packet of brewer’s dry yeast down one toilet on the bottom floor of your house once a month. The yeast will help add “good” bacteria to your septic tank and break down waste.
Can you put too much bacteria in a septic tank?
Too much of a good thing can cause problems. A septic system relies on the correct balance of bacteria to do its job. An overpopulation of bacteria can deplete the oxygen in the septic tank and turn the environment septic. A septic, septic system is one in which the ecosystem within the tank is out of balance.
How often should a septic tank be pumped?
Inspect and Pump Frequently Household septic tanks are typically pumped every three to five years.
How much does it cost to pump a septic tank?
How much does it cost to pump out a septic tank? The average cost is $300, but can run up to $500, depending on your location. The tank should be pumped out every three to five years.
What kind of sand do you use for a septic system?
Septic sand is used as an effective filtration system in modern septic systems and sewage mounds. It is produced from some of the highest quality sand & gravel, which is washed and finely screened.
How Does Drip Irrigation Treat Septic Tank Effluent?
Is it necessary to rebuild the leach fields in your area? Using leach fields as a temporary remedy is not recommended. They will ultimately begin to fail as a result of the wear and tear that they will experience. Time required for this varies widely and is highly dependent on several factors, including how much the system is utilized, how often the tank is pumped, the nature of the underlying soil, and whether the system is “abused.” Is it necessary to design a septic system? Yes, all septic systems must be developed by a soil testing business or somebody that is licensed in the state of California.
Construction of a septic system is done according to plan.
However, I’m sure there will be instances where this is not the case; Do I have to differentiate between them?
Types of Septic Systems
Septic system design and size can differ significantly from one neighborhood to the next, as well as throughout the country, due to a variety of variables. Household size, soil type, slope of the site, lot size, closeness to sensitive water bodies, weather conditions, and even municipal ordinances are all considerations to take into consideration. The following are 10 of the most often encountered septic system configurations. It should be noted that this is not an exhaustive list; there are several additional types of septic systems.
- Septic Tank, Conventional System, Chamber System, Drip Distribution System, Aerobic Treatment Unit, Mound Systems, Recirculating Sand Filter System, Evapotranspiration System, Constructed Wetland System, Cluster / Community System, etc.
This tank is underground and waterproof, and it was designed and built specifically for receiving and partially treating raw home sanitary wastewater. Generally speaking, heavy materials settle at or near the bottom of the tank, whereas greases and lighter solids float to the surface. The sediments are retained in the tank, while the wastewater is sent to the drainfield for further treatment and dispersion once it has been treated.
Septic tanks and trench or bed subsurface wastewater infiltration systems are two types of decentralized wastewater treatment systems (drainfield). When it comes to single-family homes and small businesses, a traditional septic system is the most common type of system. For decades, people have used a gravel/stone drainfield as a method of water drainage. The term is derived from the process of constructing the drainfield. A short underground trench made of stone or gravel collects wastewater from the septic tank in this configuration, which is commonly used.
Effluent filters through the stone and is further cleaned by microorganisms once it reaches the soil below the gravel/stone trench, which is located below the trench.
Gravelless drainfields have been regularly utilized in various states for more than 30 years and have evolved into a standard technology that has mostly replaced gravel systems. Various configurations are possible, including open-bottom chambers, pipe that has been clothed, and synthetic materials such as expanded polystyrene media. Gravelless systems can be constructed entirely of recycled materials, resulting in considerable reductions in carbon dioxide emissions during their lifetime. The chamber system is a type of gravelless system that can be used as an example.
The key advantage of the chamber system is the enhanced simplicity with which it can be delivered and built.
They are also well suited for use in places with high groundwater tables, where the amount of influent to the septic system is varied (e.g., at a vacation home or seasonal inn), and in areas where there is a high concentration of phosphorus and nitrogen.
Drip Distribution System
An effluent dispersal system such as the drip distribution system may be employed in a variety of drainfield configurations and is very versatile. In comparison to other distribution systems, the drip distribution system does not require a vast mound of dirt because the drip laterals are only placed into the top 6 to 12 inches of soil. In addition to requiring a big dosage tank after the sewage treatment plant to handle scheduled dose delivery of wastewater to drip absorption areas, the drip distribution system has one major disadvantage: it is more expensive.
Aerobic Treatment Unit
An effluent dispersal system such as the drip distribution system may be employed in a variety of drainfield configurations and is quite inexpensive. In comparison to other distribution systems, the drip distribution system does not require a significant mound of dirt since the drip laterals are placed inside the top 6 to 12 inches of soil. In addition to requiring a big dosage tank after the sewage treatment plant to handle scheduled dose delivery of wastewater to drip absorption areas, the drip distribution system has one major disadvantage: it is more expensive than other wastewater treatment systems.
Using mound systems in regions with short soil depth, high groundwater levels, or shallow bedrock might be a good alternative. A drainfield trench has been dug through the sand mound that was erected. The effluent from the septic tank runs into a pump chamber, where it is pumped to the mound in the amounts recommended. During its release to the trench, the effluent filters through the sand and is dispersed into the native soil, where it continues to be treated. However, while mound systems can be an effective solution for some soil conditions, they demand a significant amount of land and require regular care.
Recirculating Sand Filter System
Sand filter systems can be built either above or below ground, depending on the use. The effluent is discharged from the septic tank into a pump compartment. Afterwards, it is pushed into the sand filter. The sand filter is often made of PVC or a concrete box that is filled with a sand-like substance. The effluent is pushed through the pipes at the top of the filter under low pressure to the drain. As the effluent exits the pipelines, it is treated as it passes through the sand filtering system.
However, sand filters are more costly than a standard septic system because they provide a higher level of nutrient treatment and are thus better suited for areas with high water tables or that are adjacent to bodies of water.
Evaporative cooling systems feature drainfields that are one-of-a-kind. It is necessary to line the drainfield at the base of the evapotranspiration system with a waterproof material. Following the entry of the effluent into the drainfield, it evaporates into the atmosphere. At the same time, the sewage never filters into the soil and never enters groundwater, unlike other septic system designs. It is only in particular climatic circumstances that evapotranspiration systems are effective.
The environment must be desert, with plenty of heat and sunshine, and no precipitation. These systems perform effectively in shallow soil; but, if it rains or snows excessively, they are at risk of failing completely.
Constructed Wetland System
Construction of a manufactured wetland is intended to simulate the treatment processes that occur in natural wetland areas. Wastewater goes from the septic tank and into the wetland cell, where it is treated. Afterwards, the wastewater goes into the media, where it is cleaned by microorganisms, plants, and other media that eliminate pathogens and nutrients. Typically, a wetland cell is constructed with an impermeable liner, gravel and sand fill, and the necessary wetland plants, all of which must be capable of withstanding the constant saturation of the surrounding environment.
As wastewater travels through the wetland, it may escape the wetland and flow onto a drainfield, where it will undergo more wastewater treatment before being absorbed into the soil by bacteria.
Cluster / Community System
In certain cases, a decentralized wastewater treatment system is owned by a group of people and is responsible for collecting wastewater from two or more residences or buildings and transporting it to a treatment and dispersal system placed on a suitable location near the dwellings or buildings. Cluster systems are widespread in settings like rural subdivisions, where they may be found in large numbers.
Drip Septic System
It is a decentralized wastewater treatment system that is under some sort of community ownership that gathers wastewater from two or more residential or commercial buildings and transports it to a treatment and dispersal system that is placed on a suitable site near the residences or buildings. Cluster systems are widespread in settings such as rural subdivisions, where they may be found in large numbers.
There are three main components to a drip septic system:
- The sewage treatment plant
- The lift tank, which is comprised of a pump and filtration system. The wastewater is distributed uniformly through the tube and the soil by the pump and lift station
- Nevertheless, The dispersion unit, which comprises of a supply and return line
- And the distribution unit
It is equipped with perforated tubing, which is used to transport effluent to the soil. They are referred to as “drip emitters,” and they are spaced at intervals of 12-24 inches apart, allowing wastewater to soak into the soil as it passes through them. The tubing is linked to a feed line on one end and a return line on the other, which allows the system to be back cleansed on a regular basis without the need for human intervention. The system is also equipped with a control panel, which keeps track of pressure fluctuations, temperature fluctuations, pump performance, and daily wastewater flow.
How to maintain your drip septic system
It is critical to clean the septic tank on a regular basis in order to eliminate the accumulated sludge and scum that has collected. Any system that includes a septic tank is necessary, but drip septic systems are considerably more critical because of the amount of water they require. Several filters in drip septic systems are susceptible to becoming clogged with solids, and the drip tubing itself has tiny pores that can become clogged with particles.
Other key components which require maintenance are:
- Each year, the filters must be cleaned manually or replaced with new ones. Solids can accumulate in the drip tube perforations, causing them to get clogged. Back flushing the tube on a regular basis is performed automatically by the system to assist prevent this problem. It may, however, be necessary to manually back-flush them, or the tubing itself may need to be replaced, if they remain clogged in spite of these efforts.
Manual cleaning or replacement of the filters is required once a year. Occasionally, particles might clog the openings in the drip tubing.
For the purpose of preventing this problem, the system automatically back flushes the tubing on a regular basis. It may, however, be necessary to manually back-flush them, or the tubing itself may need to be replaced, if they remain clogged after these efforts.
Taking Care of Drip Distribution Systems
Receive articles, news, and videos about Systems/ATUs sent directly to your email! Now is the time to sign up. Systems/ATUs+ Receive Notifications A drip dispersion system is a pressurized effluent distribution system with a tiny diameter that is capable of delivering small, accurate dosages of effluent to the soil surrounding the drip distribution pipe. drip dispersion operates on the same fundamental principles as any other soil-based treatment system: filtration and bacterial breakdown of the effluent are the primary functions.
Drip distribution systems are designed to disperse sewage uniformly throughout a vast region, ensuring that no single place receives an excessive amount of effluent.
It’s all dribble
Operation and maintenance
Primary treatment tanks and pump tanks should be examined and serviced on a regular basis, as needed. The manufacturer of the drip system and the individual components of the system determine the recommended maintenance chores for the system. Consultation with the manufacturer should be sought, and maintenance should be carried out in line with the manufacturer’s specifications. It is recommended that inspections of the drip system components be carried out at least twice a year. Cleaning and maintaining drip distribution systems is comparable to cleaning and maintaining other types of equipment.
The following should be included in the service:
- Taking care of the filters
- System testing to confirm that the flushing and alarm systems are operating properly
- Performing a visual inspection of the flush and vacuum release valves, and cleaning them if required
- Examining pressure-reducing valves to determine whether or whether they require cleaning
- In order to ensure that the dosage volumes recorded on the water meter are appropriate in compliance with the system design dose, Checking the capacity of the pump’s discharge
- Ensuring that there are no wet or moist areas on the surface of the distribution field
Drip system components can be damaged by rodents in particular regions where they are active. Glovers have been observed eating through driplines and burrowing into valve boxes or other enclosures, where they can damage components or simply fill the valve box with dirt, as has been documented. Rodents will not burrow toward a dripline, according to one dripline maker, if the round is maintained consistently wet, according to another (one reason for high-frequency dosing). When a drip system is charged and tested and then left out of service for a period of time, such as when a system is used seasonally or when a system has been in continuous operation but is temporarily shut down for a family vacation, this might still cause an issue.
Is Drip Distribution Right for Your Site?
The installation of drip systems is shallow, making them excellent for areas with tough or slow draining soils. Featured image courtesy of the American Manufacturing Company
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Receive articles, news, and videos about Systems/ATUs sent directly to your email! Now is the time to sign up. Systems/ATUs+ Receive Notifications It’s been over two decades since drip distribution first appeared on the scene. During a study and demonstration effort looking into alternate systems for Minnesota in the early 2000s, I was associated with the first system of this sort I was involved with. The system, in different incarnations, had existed for a long time before to then, mostly in southern states or in areas where irrigation was widely employed.
This enables for a more level distribution of effluent across a larger region because of the increased distribution. In the country’s hottest and driest regions, one of the most important goals is to keep cool.
This article is part of a series on drip distribution:
- Drip Distribution: Is it the Right Choice for Your Site? Making a decision on which filter to use for a drip distribution system
- Choosing the proper size for a drip distribution system
- Designing a Drip System: Some Pointers
- Site preparation for the installation of drip distribution systems
- Tips for Using the Drip System OM
- Drip System O M is used to control the flow of water.
Maintenance for Drip Dispersal Systems
Drizzle dispersion systems require three different types of maintenance. The first is routine maintenance. Pretreatment, pumping and hydraulic unit, absorption area, and drop dispersal area are all components of the maintenance process that should be broken down. Pretreatment often consists of either septic tanks or aerobic treatment facilities, depending on the situation. Both need regular observation. A passive kind of treatment, septic tanks need less upkeep than other types of treatment. It is not the number of projected residents or the amount of water they will use that determines the size of a septic tank; it is the number of bedrooms in a residence.
It is hard to calculate an accurate timetable for when to pump a tank or when to empty a tank based on these factors.
Types of Septic Systems
When used properly, a septic tank can offer initial treatment for wastewater by trapping and preventing the movement of soil clogging elements (such as solid waste or fats, oils, and grease, among other things) to the drainfield. Septic tanks create an environment in which some elements can be lowered even more by microbial breakdown, which occurs in the tank itself. It is advised that you pump out your septic tank at least once every 2 – 5 years. There are one or more drainlines connected to a distribution device (distribution box or D-Box, pressure manifold) and a distribution device.
When compared to a gravel drainline, certain gravel-less ditches allow for a 25 percent reduction in overall drainline length, which can result in a reduction in the size of the septic system’s drainfield.
Conventional Gravity Septic System
It is the most basic type of onsite wastewater system and requires deep useable soil depths to be installed in order to function properly (30 inches). A traditional gravel system is made up of two components: a septic tank and a drainfield. The system is installed in such a way that wastewater may be moved throughout the system with the help of gravity. Gravity systems that are conventional in design are always the top choice because to their reduced cost and minimal maintenance needs. Almost any sort of gravel or gravel-less drainline can be used in the drainfield.
Conventional-Pump Septic System
These systems make use of a separate pump tank and pump to ensure that wastewater is correctly distributed to the drainlines. They are most commonly employed when the drainfield is located uphill from the residence. Almost any sort of gravel or gravel-less drainline can be used in the drainfield. The average cost of a 4-bedroom system is between $5,000 and $6,000.
Pressure Distribution Systems
When the drainfield is located uphill from the residence, these systems make use of a separate pump tank and pump to correctly transport wastewater to the drainlines.
They are most commonly employed in this situation. Almost any form of gravel or gravel-free drainline can be used in the drainage field. A four-bedroom system will typically cost between $5,000 and $6,000 to install.
Pressure Manifold Septic System
The average cost of a 4-bedroom system is between $6,000 and $8,000.
Low-Pressure Pipe (LPP) Septic System
The average cost of a 4-bedroom system is between $12,000 and $15,000.
Drip Disposal Septic Systems
The use of drip disposal systems is typically reserved for locations with useable soil depths ranging from 18 to 24 inches. A septic tank, a pump tank, a hydraulic unit, and a drip tubing drainfield are all components of the system. The average cost of a 4-bedroom system is between $17,000 and $25,000 dollars.
Drip Disposal Systems – Aerobic Treatment
They are identical to anaerobic systems, with the exception that they feature an aerobic pre-treatment unit that processes the wastewater before it is discharged. These methods are used on the most marginal soils, with acceptable soil depths ranging from 13 to 18 inches on these soils. Septic tanks, a pump tank/aerobic pre-treatment unit, a hydraulic unit/filter module, and drip tubing drainfields are all components of the overall system. The average cost of a four-bedroom system is $40,000 per system.
Learn more about Septic Systems and Soils Testing
Knowing the basics of septic systems, whether you’re installing or living with one, is beneficial when making decisions about your home. If you follow these procedures, you will be able to extend the life of your system, learn what to do if something goes wrong, and analyze your alternatives if you ever need to expand your system due to a home renovation project. This type of sewage treatment system, which is utilized by one in every five households in the United States and almost half of all households in the South, cleans wastewater equally as well as municipal systems in cities.
When it comes to septic systems, the average life expectancy is 25 to 30 years.
How septic systems work
All septic systems are composed of two major components: a tank in which particles settle to the bottom and a drainfield (also known as a leachfield) in which water dissipates after passing through it. Detailed information regarding the sort of system you have should have been included in the documents you got when you purchased your home. If the specifics have become hazy due to the passage of time, get out those old documents and do some research. It’s possible that your local health department or state environmental agency has backup data as well.
According to typical septic systems, gravity moves wastewater from the home into the septic tank, which then transports it to a drainage field. The septic tank is a large underground container that is often built of concrete, polyethylene, or glass fiber. Water collects there for a long enough period of time for the components to separate. Every few years, a septic pumping firm will come in and remove the greases and oils that have risen to the surface as scum, as well as the solids that have sunk to the bottom as sludge, and transport them to an approved disposal location.
Drainage systems consist of perforated pipes or drain tiles that are sunk in trenches or laid on a gravel bed, and they must be kept clear of trees and plants to prevent their roots from damaging them.
You’ll need an alternative system if your soil type, property size, or proximity to a wetland prevents you from using a conventional system. An alternative system is one that includes an improved septic tank, drainfield, or both. These systems are more expensive to install than simple systems, however the cost varies greatly based on your location, your local environmental standards, and the technology you require to be installed. Here are a few examples of the most prevalent kinds. Treatment alternatives are number one.
It is possible to get away with a smaller drainfield—one that is built on a site that does not drain well—or with a site that is adjacent to a lake or stream, in which case you must adhere to tougher environmental regulations.
OWTS: Subsurface Drip Distribution – Texas A&M AgriLife Extension
Our work has a positive impact on the lives of Texans as well as the state’s economy. View Economic Impacts» for further information. Written by Bruce Lesikar Water is distributed to the grass using a system of tubing that is placed below the ground surface, using a subsurface drip system. An irrigation system is composed of four major components: a treatment device, a pump tank, a filtration device, and a drip distribution system, in that order. There are a variety of treatment devices available, including an aerobic unit, a sand filter, a trickling filter, and a built wetland, among other options.
The bare minimum in treatment is a septic tank, which is used to settle the solids.
The water is stored in the pump tank until it is needed.
Most locations can benefit from the installation of a drip distribution system. It is suitable for use in clay soils, shallow soils, and areas with moderately saturated conditions, among other things. In comparison to a spray distribution system, it requires just one foot of unsaturated soil below the drip tubing and requires less surface area. The drip system distributes water evenly over the grass, allowing it to be recycled by the plants in the landscaping. On relatively steep slopes, pressure-compensating emitters can be employed to provide illumination.
In order for the drip system to function properly, there must be at least one foot of unsaturated soil underneath the drip tubing, which is often put 6 to 8 inches below the surface.
It is possible for the drip system to become clogged with organic waste and particles if the system is not properly maintained since the emitters are so tiny. Drip distribution systems require an ongoing maintenance contract to ensure that the drip field is properly operated and maintained.
How to keep it working
- In order to avoid particles from being dosed into the drip tubing, the treatment system should be pumped at least once every 2 to 3 years. Examine the filtration system on a regular basis
Installation expenses typically range from $4,000 to $10,000, depending on the kind of pretreatment, filtration equipment, and monitoring system used. The pretreatment system accounts for a significant portion of the total installation expenses. A drip distribution system typically costs between $2,000 and $3,000 to install. The cost of upkeep is around $300 to $600 per year, which covers quarterly pump-outs, power, and any necessary repair visits as needed. Download a printer-friendly version of this publication by clicking on the following link: OWTS: Subsurface Drip Distribution (On the Ground) Do you have a question – or do you require the assistance of an expert?
Alternative & Innovative Septic Systems
An Alternate Septic System is a system that has been approved by the New Hampshire Department of Environmental Services (NHDES) subsurface Bureau for a specific site with Site Conditions that would make a traditional type system ineffective. holding tank: A holding tank is a concrete or plastic tank that is buried in the ground and requires constant pumping to function properly. Privies (Outhouse): A small disposal area created above the estimated seasonal high water table level to accommodate human waste.
Using Gray Water Systems: This system can only be used with gray water, which is described as water from the sink or shower.
An innovative or green system is a design for an aseptic system that takes the environment into consideration. These systems are smaller in size and are regarded a more modern approach to dealing with small, difficult-to-design locations, such as lake front homes, island properties, and other similar situations. Drop Dispersal: Drop Dispersal systems are a type of drip irrigation system that is simple to install and may be utilized all year round. The system has low profile, which allows it to be used in most circumstances without the need for a mound system.
Manufacturers for the Drip Dispersal are:
Septic systems that are aerobic or green in nature take into consideration the environment by pretreating wastewater before it is disseminated in the earth. These systems are extremely compact in size and provide an innovative solution for dealing with sewage on difficult-to-design lots, such as lakefront homes, island properties, and other similar sites.
Manufacturers for the Aerobic Pretreatment Systems are:
A three-compartment tank is being erected for the purpose of distributing pressure. A pressure distribution lateral is being erected in three-foot-wide trenches employing graveless chambers to distribute pressure. Clark, Skamania, and Cowlitz Counties are home to a large number of them. This is a manifold that provides for flow control of each of the pressure distribution laterals in a pressure distribution system. An extensive pressured drainfield system, including many graveless chamber laterals, was recently completed and tested.
Prior to backfilling, a “drip” drainfield was built.
They are more expensive to build and require more maintenance than a system with a graveless chamber. The “headworks” for a drip drainfield are seen here. The complexity of these systems is more than that of a normal “pressure” system, as seen above. The command and control
- Textile Filters (AdvanTex)
- Glendon Pods
- Sand Filters (which are no longer commonly built, but there are numerous in the ground)
- Sand Mounds
- Aerobic Treatment
Advanced treatment systems for residential projects generally vary in price from $13,000 to $20,000, depending on their complexity. They can be higher if the structure is larger than usual or if the location has extremely challenging limitations. Only in extremely rare instances might a home system exceed $50,000 in cost. This is, however, a very unusual occurrence. An underground box filled with sand and drainrock collects pressured effluent from the septic tank and transports it to the sand filter.
During the filtering process, the unclean effluent passes through sand and settles in a sump at the bottom.