As wastewater flows into the septic tank, bacteria decompose some solids. Heavy solids sink to form a sludge layer while oils and grease float to the top to become a scum layer.

The liquid waste in the middle, called effluent, exits through an outlet into a drain or absorption area (also known as a leach field). Bacteria in the drain field further treat the sewage and regenerate the soil. Click Here to learn more.

A septic tank is a buried, watertight container through which domestic wastewater flows for basic sewage treatment. It holds the wastewater long enough to allow solids to settle down and form sludge, while oil and grease float up to the top as scum. Compartments and a T-shaped outlet prevent the sludge and scum from exiting the septic system and traveling into the drainfield area where it could cause soil contamination. The liquid wastewater (effluent) then exits the septic tank into the absorption field for further sewage treatment.

A baffle wall or divider separates compartments in your septic tank and keeps most floating scum and settled solids from clogging the inlet pipe. The opening on the inlet pipe is located about midway between the floor and the tank roof. The baffle wall also reduces agitation of the wastewater, which helps solids to settle faster and more thoroughly.

Wastewater leaves your septic tank through a perforated pipe that is buried in a drainfield, sometimes known as a soil absorption field or leachfield. The piping network distributes the wastewater into trenches that are spaced to match your home’s plumbing design and the size of the absorption field. The septic tank’s anaerobic digestion process eliminates fecal bacteria and organic material, and the soil absorbs and neutralizes any remaining toxins.

Your septic system is not designed to treat all of the contaminants in your wastewater. Those that remain must be eliminated from the septic system or removed from your house, usually by installing a treatment plant. The best way to keep your septic tank and absorption field in good condition is to limit your household wastewater usage.

Don’t construct structures, such as patios, decks, sheds, detached garages and above-ground or in-ground swimming pools over or near the septic tank and distribution box. Excess water can fill soil pore spaces, taking up valuable space needed for aeration and wastewater flow. Keep mowers, snowblowers and other equipment away from the septic tank and drainfield areas to prevent damage to your septic system and its components. Plant grass and other shallow-rooted plants over the absorption field. Keep children, pets and livestock away from the drainfield area.

Sludge Disposal

The wastewater inside the septic tank passes through screening chambers that strain out large debris such as branches, rags and plastics. The faecal matter that is too heavy to sink settles in the bottom of the tank, where it forms a layer known as sludge. Lighter solids such as fats and oils float to the top of the waste stream, where they are partially decomposed by bacteria into a clear layer of scum.

The liquid layer in the middle of the tank contains the rest of the wastewater, along with waste particles too small to sink. Bacteria do their best to break down these solids, but they can’t handle everything. Eventually, these solids accumulate to the point where they block the flow of wastewater through the system.

This is when it’s time to pump the septic tank. A professional will suck out the sludge and liquid waste, called septage, from the septic tank. The septage is then trucked away to a public or private wastewater treatment plant, where it goes through the same treatment process as standard municipal sewage.

When it comes to septic tanks, a regular desludging schedule is important to keep the system working properly. A septic tank’s sludge accumulation rate depends on the size of the tank, the occupant and how much is used in the household.

A new equation has been developed to define the optimum desludging frequency. It takes into account the average daily faecal production per person, tank size and occupancy and the amount of solids in the septic tank.

Septic tank sludge accumulation rates decrease over time. This means that the septic tank will require a desludging less often as the volume of solids decreases. The rate of solids accumulation also depends on how much is being put into the septic tank, including the use of garbage disposals. Heavy use of a disposal can lead to more scum formation and requires the tank to be pumped more frequently. In addition, the disposal of cigarette butts and other solid waste can increase scum and sludge formation. These things can also clog plumbing and cause the septic tank to need pumping more frequently.

Venting Gases

In a standard septic tank, a partially separated compartment is used to capture and decompose organic materials. Floating parts such as greasy substances and toilet paper remain in the first compartment while solids settle at the bottom of the tank, which is known as the sludge layer. Solids are broken down by microorganisms living in the septic tank. This is called aerobic digestion. This process releases gases, including hydrogen sulfide (known for its rotten egg smell) and methane. These gasses are then released through a vent. Venting the gasses is necessary for the safety of the house occupants and to prevent the build-up of pressure that could cause a pump failure in the wastewater system.

The septic tank is also an effective filter, keeping bacteria and other organisms from reaching the surface waters and groundwater. This is particularly important in shallow and sandy soil areas where it is possible for pathogenic bacteria to enter natural water sources.

A typical septic tank is made from concrete, though there are also models made of fiberglass and plastic. It is buried underground and designed to hold waste from a single household. The size of a septic tank depends on the number of bathrooms and bedrooms in a house.

Most septic tanks are rectangular and contain baffles to separate the wastewater from the sludge. The baffles are usually made of a durable material such as fiberglass or polyethylene. They have inspection ports over each one and are covered by a plastic lid that is about 4 inches in diameter. The tanks also have larger manholes for pumping.

In a septic tank, the sludge is a thick layer at the bottom of the tank. The sludge contains fats, oils and greases as well as solids from the toilet, dishwasher and kitchen sinks. The septic tank’s microorganisms break down these substances, which rise to the top of the wastewater. The sludge is then digested by the microorganisms and mixed into the sewage.

The wastewater from a septic tank flows into a drain field, which is a series of trenches filled with washed gravel or stone. The gravel provides a surface for natural filtration of the bacteria and other contaminants from the sewage. The drain field is connected to the septic tank through pipes, which are typically built of heavy-duty PVC or polyethylene. A pipe runs from the septic tank to vent odors and gases outside of the house. A septic system requires regular pumping, inspection, and maintenance by a professional septage waste transporter.

Pumping

Septic tanks provide a lot of convenience by eliminating the need to pay a water and sewer bill. However, they do come with added responsibilities. They must be pumped out regularly, and the septic system itself must be maintained properly. If you live in a house with a septic tank, then it’s crucial that you know the do’s and don’ts of your septic system to ensure that it works correctly and doesn’t cause problems for you or your neighbors.

Septic systems use a network of pipes to treat the wastewater that leaves your home. The piping network, also called the drain field or absorption field, is designed to percolate the wastewater into the soil where the bacteria work to remove any remaining impurities. This helps to clean the water that ultimately enters groundwater and surface water.

When raw wastewater enters the septic tank, it is mixed with the sludge layer and a floating scum layer. The tees that extend from the inlet and outlet ports of your septic tank create hydraulic pressure which pushes the sludge layer into the float box and the scum layer into the inlet port to prevent solid waste from entering your drain field. This allows the septic tank to operate efficiently.

If you’re concerned about the amount of solid waste that is entering your septic tank, have it pumped out before it gets too full. The frequency of pumping depends on a variety of factors, including tank size, household size, and waste generation rates. However, it’s recommended that you have your septic tank pumped every three to five years.

You can help extend the life of your septic system by only flushing septic-safe items down the toilets. This includes non-biodegradable products such as cigarette butts, cotton swabs and wipes, menstrual hygiene products, condoms, and pet waste. It’s also a good idea to avoid excessive water usage, as this can overload the septic tank and lead to wastewater overflowing into your home. Finally, keep trees and other large plants at least 30 metres away from the septic tank and soakaway area. This will reduce the risk of roots clogging the absorption field and reducing its effluent flow.