- What is a septic system?
- How does a septic tank work?
- How to find a septic tank?
- What does an inspector look for?
- How often to pump septic tank?
- Sewage treatment or wastewater treatment process
What is a septic system?
Septic tanks are a necessary item in any residence. They are a self-contained, underground waste water treatment system to treat and dispose of household waste water. Septic tanks operate by holding the waste water in the tank long enough for solids and liquids to separate. They are not complicated designs and are highly efficient and not difficult to maintain, though they should be inspected and pumped on a periodic basis.
For a four-bedroom home with a daily average flow of around 480 gallons, it takes about 24 to 48 hours for solids to settle. A typical 1,000 gallon tank will take about two days for solids to settle, though solids do accumulate. If there is too much accumulation, the tank must be pumped. Household practices and water usage vary greatly as does the size of septic tanks but regular inspections should be performed for an efficiently operating tank. Only a certified inspector should perform the inspection.
How Does a Septic Tank Work?
A septic system is a self-contained waste water treatment system that all homes have and consists of a house sewer drain, septic tank, distribution box and a drainage field. Most septic tanks are made of concrete though some are made of plastic, steel or fiberglass. They are located underground and away from the house and where vehicles cannot run over it. A typical septic tank holds about 1,000 gallons (4,000 liters) of water and must be watertight. From the inlet pipe at one end, waste water flows into the septic tank and exits the other end though the outlet pipe, both usually made of durable plastic.
The below illustration indicates what a tank looks like in cross-section:The illustration shows three layers: a sludge layer at the bottom, water above it and a scum layer on top. Solids form the sludge layer. The water contains bacteria and certain chemicals such as nitrogen and phosphorous. Your home has sewer pipes running from the bathrooms and kitchen from where the waste water flows to the septic tank as shown in this illustration:
Septic tanks are designed so that a quiet waste water pond is created where bacteria, yeast and fungi breeds. Solids sink to the bottom and are attacked by bacteria though methane and other noxious gases are produced as a by-product. To prevent these gases from flowing back into your home, sinks have P-traps that hold water in the lower loop and force the gases up a vent pipe. Most homes have vent pipes sticking up through the roofs.
Waste water enters the septic tank from your house and displaces the water there. The tank separates the solids and stores them where they decompose from the bacterial process. The effluent waste water is then sent out through the outlet pipe to the drain field. The drain field consists of buried perforated pipes surrounded by gravel and dirt. The below illustration is of an overhead view of a home, septic tank, distribution box and drain field:
Drain field pipes are about 4 inches (10 centimeters) in diameter and are underground in trenches that are 4 to 6 feet (1.5 m) deep and 2 feet (0.6 m) in width. Gravel is at the bottom and is covered over by dirt, looking like this: Drain fields absorb, dispose of and treat the septic tank effluent. Its size depends on the soil conditions with a hard clay ground requiring a much larger drain field. The effluent eventually evaporates and operates as a purification process that feeds plant life or becomes part of the groundwater. The entire system is an entirely passive system, operating by gravity alone with the waste water from your house flowing down to the tank out to the drain field.
- Checking for Accumulation of Solids The inspector’s task is to determine if there is too much accumulation of solids in the tank. A tool that an inspector uses is a “Sludge Judge” or something similar. This particular product is a clear, plastic hollow pole with a stopper on the end and with markings at 1-foot intervals. The inspector inserts the device to the bottom of the tank so that the wastewater and solids enter it, giving the inspector a method of measuring the levels of the solids and liquids. Guidelines state that the maximum level of solids in a septic tank is 1/3 of the liquid depth. If the solids accumulation exceed this, the tank should be promptly pumped.
- Watertightness Septic tanks are made of concrete, fiberglass or even plastic. It is essential that they be watertight to avoid contamination of groundwater and so that groundwater does not enter the tank or it could overfill. To check for watertightness, the tank must be pumped so it can be visually inspected.
- Leaks and Infiltration Along with pumping the tank to check for watertightness, the inspector looks at either baffles or tees. These products slow the wastewater entering the septic tank so that a calm environment is secured for solids to settle. These products must be properly connected to the inlet and outlet pipes, which are usually made of plastic. A baffle is either concrete, fiberglass or plastic, depending on the material used for the septic tank. If a concrete baffle is corroded or cracked, a tee is fitted to the tank. Tees are made of plastic like the inlet and outlet pipes.Once the tank is pumped, the inspector checks for leaks in the inlet and outlet pipes. If water is running into the tank, there is likely a plumbing leak in the home or a problem with the inlet pipe. Should water be draining back from the outlet pipe, the drainage field could be clogged.
- The Effluent Filter Effluent filters, if used, substantially filter solids down and increase the efficiency and life of your septic system. Located on the outlet side of the tank in the outlet tee, these filters should be serviced by pulling it and hosing the contents back into the septic tank.
- Manhole Risers One way to easily locate and to access your septic tank is to use a manhole riser. These are made of durable plastic and are installed to come to ground level. These are checked for cracks and intrusions and to see if they are properly secured to avoid unauthorized access.
Have your septic tank routinely inspected. Florida Department of Health recommends to pump your tank every 3-5 years. A septic tank inspection is not commonly considered as part of a property transfer inspection and many homeowners neglect this important step in routine home maintenance practices. Avoid unwanted and messy problems with your septic system by having your septic tank inspected on a regular basis.
Water is our most precious resource. So much of our water that is used by businesses, homes and industries must be treated before being returned to the environment or we would be overwhelmed by pollutants and bacteria that would create an unsafe and possibly unlivable world. Wastewater treatment is sewage treatment. Billions of gallons of sewage and wastewater is produced daily that treatment plants handle by reducing the pollutants found in wastewater to levels that nature can manage. Wastewater consists of human waste, chemicals and soaps, all emanating from our toilets, sinks, washing machines, showers and industrial uses. Used motor oil is sometimes poured into drainage or sewers along with common storm runoff that contains bacteria and other harmful toxins from roadways and roofs that empty into our lakes, rivers and bays. Reasons to Treat Wastewater If we did not treat wastewater, our health would be seriously undermined leading to infectious diseases, cancer, birth defects and have an adverse effect on our food supplies. There are a host of important reasons for keeping our water supplies clean:
- Fisheries Fish and plants are essential to our oceans, rivers and lakes. The lack of clean water could seriously disrupt these ecosystems as well as cause substantial damage to the fishing industry and sport fishing activities.
- Wildlife Habitats Aquatic life depends on clean beaches, marshes and shorelines. Untreated wastewater would undermine these critically important habitats for migratory birds who use these areas for feeding and resting or else breeding practices could be jeopardized.
- Recreation and Quality of Life Millions of us flock to beaches and lakes every summer with countless local communities dependent on such tourism for their existence. Coastal areas and lake properties are extremely attractive places to visit, live and work and offer many recreational activities such as boating, swimming, fishing and picnicking.
- Health Concerns The importance of treating wastewater and having a clean water supply cannot be emphasized enough since so many of us leave so close to water. Untreated wastewater carries serious diseases.
- Our Environment and Wastewater Pollutants Unless wastewater is effectively treated, the impact on human life and the environment could be catastrophic. This includes significant repercussions to ecosystems, aquatic and wildlife populations, beaches, marshes, recreational water activities, and lead to serious restrictions placed on the seafood industry. It could also easily contaminate our drinking water. Environment Canada has examples of wastewater pollutants and their harmful consequences on ecosystems and our health:
- Organic matter and debris that is untreated and left to decay can deplete oxygen in lakes and cause fish and aquatic plants and other organisms to die;
- Too much phosphorous and nitrogen, that can produce ammonia, from wastewater can lead to eutrophication, which is the over-fertilizing of receiving waters. Substantial overgrowth of algae can overwhelm an ecosystem and harm water quality, food resources and habitats and decrease oxygen levels in water, killing large numbers of fish. Excess nitrogen can alter plant growth and adversely affect the health of forests and soils;
- Chlorine and chloramines are used to treat drinking water supplies as disinfecting agents but are toxic to fish even at low concentrations;
- bacteria and harmful pathogens pollute beaches and contaminate shellfish, restricting recreational activities and causing concern about drinking water and shellfish consumption;
- toxic metals such as mercury, lead, cadmium, chromium and arsenic can have harmful and deadly consequences for animal species;
- chemicals and substances from shampoos, nail polishes, pharmaceutical and other artificially created products found in wastewater effluents can cause serious threats to human, wildlife and aquatic systems if left untreated.
Why Treat Wastewater The treatment of wastewater is essential to maintaining our health and numerous industries and in protecting our precious wildlife and aquatic populations from the toxic effects of wastewater pollutants. Wastewater treatment is designed to remove suspended solids before the effluent is returned to the environment. Without treatment, decaying solids would deplete oxygen and harm plants and animals that live in water. By “primary treatment” about 60% of suspended solids are removed, which also results in mixing or stirring the wastewater so that oxygen is put back into the treated water by the aeration process. “Secondary treatment” of wastewater can remove 90% of the suspended solids.
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