Frequently Asked Questions
What is a Septic Tank?
A septic tank is a key component of the septic system, a small-scale sewage treatment system common in areas that lack connection to main sewage pipes provided by local governments or private corporations. Other components, generally controlled by local governments, may include pumps, alarms, sand filters, and clarified liquid effluent disposal methods such as a septic drain field, ponds, natural stone fiber filter plants or peat moss beds.
What does the term “Septic” mean?
The term “septic” refers to the anaerobic bacterial environment that develops in the tank which decomposes or mineralizes the waste discharged into the tank. Septic tanks can be coupled with other onsite wastewater treatment units such as biofilters or aerobic systems involving artificially forced aeration.
How does a Septic Tank work?
A septic tank consists of one or more concrete or plastic tanks of between 4000 and 7500 liters (1,000 and 2,000 gallons); one end is connected to an inlet wastewater pipe and the other to a septic drain field. Generally these pipe connections are made with a T pipe, allowing liquid to enter and exit without disturbing any crust on the surface. Today, the design of the tank usually incorporates two chambers, each equipped with a manhole cover, and separated by a dividing wall with openings located about midway between the floor and roof of the tank.
Wastewater enters the first chamber of the tank, allowing solids to settle and scum to float. The settled solids are anaerobically digested, reducing the volume of solids. The liquid component flows through the dividing wall into the second chamber, where further settlement takes place. The excess liquid, now in a relatively clear condition, then drains from the outlet into the leach field, also referred to as a drain field or seepage field, depending upon locality. A percolation test is required prior to installation to ensure the porosity of the soil is adequate to serve as a drain field.
The remaining impurities are trapped and eliminated in the soil, with the excess water eliminated through percolation into the soil, through evaporation, and by uptake through the root system of plants and eventual transpiration or entering groundwater or surface water. A piping network, often laid in a stone-filled trench (see weeping tile), distributes the wastewater throughout the field with multiple drainage holes in the network. The size of the leach field is proportional to the volume of wastewater and inversely proportional to the porosity of the drainage field. The entire septic system can operate by gravity alone or, where topographic considerations require, with inclusion of a lift pump. Certain septic tank designs include siphons or other devices to increase the volume and velocity of outflow to the drainage field. These help to fill the drainage pipe more evenly and extend the drainage field life by preventing premature clogging.
A properly designed and normally operating septic system is odor-free and, besides periodic inspection and emptying of the septic tank, should last for decades with minimal maintenance.
How long should my Septic Tank last?
A well designed and maintained concrete, fiberglass, or plastic tank should last about 50 years.
How is a Septic Tank emptied?
When a septic tank is emptied, the accumulated sludge (septage, also known as fecal sludge) is pumped out of the tank by a vacuum truck. How often the septic tank must be emptied depends on the volume of the tank relative to the input of solids, the amount of indigestible solids, and the ambient temperature (because anaerobic digestion occurs more efficiently at higher temperatures), as well as usage, system characteristics and the requirements of the relevant authority. Some health authorities require tanks to be emptied at prescribed intervals, while others leave it up to the determination of an inspector. Some systems require pumping every few years or sooner, while others may be able to go 10–20 years between pumping. An older system with an undersize tank that is being used by a large family will require much more frequent pumping than a new system used by only a few people.
Not sure if your tank needs to be emptied, cleaned or serviced? Give us a call:
What can cause a Septic Tank to need servicing?
- Excessive dumping of cooking oils and grease can cause the inlet drains to block.
- Flushing non-biodegradable waste items down the toilet such as cigarette butts, cotton buds/swabs or menstrual hygiene products(e.g. sanitary napkins or tampons) can cause a septic tank to clog and fill rapidly.
- Using the toilet for disposal of food waste can cause a rapid overload of the system with solids and contribute to failure.
- Certain chemicals may damage the components or the bacteria operating in a septic tank, especially pesticides, herbicides, materials with high concentrations of bleach or caustic soda (lye) or any other inorganic materials such as paints or solvents.
- The flushing of salted water into the septic system can lead to sodium binding in the drain-field.
- Roots from trees and shrubbery growing above the tank or the drain-field may clog and/or rupture them.
- Playgrounds and storage buildings may cause damage to a tank and the drainage field.
- Excessive water entering the system will overload it and cause it to fail.
- Very high rainfall, rapid snowmelt, and flooding from rivers or the sea can all prevent a drain field from operating, and can cause flow to back up, interfering with the normal operation of the tank.
- Over time, biofilms develop on the pipes of the drainage field, which can lead to blockage.