Building Surveyor Comments on How Septic Tanks Work

HOW SEPTIC TANKS WORK

Tanks are designed to allow waste liquids to flow through the tank and enter a percolation area without causing damage to the environment. Waste waters enter the tank and the solids to sink to the bottom. Smaller particles float to the surface creating a scum. Most of the waste decomposes through natural aerobic and anaerobic processes. Solids in the tank are normally emptied every year.

Emptying Frequency.

There is no hard and fast rule, but immobiliensachverständiger for a tank to work efficiently the sludge (solids) needs to be removed based on the capacity of the tank and the use it is subjected to. The frequency of “de-sludging” will depend on size of the property and the number of occupants. However, most will require emptying at least once a year are in the case of modern biocycle system or secondary treatment systems according to the manufacturers specifications.

Surveyors tips in improving efficiency of tanks.

• Don’t dispose of chemicals, disposable nappies or hygiene products down the toilet.

• Don’t use large quantities of biological cleaning agents and bleach.

• Don’t clean down internal areas of the tank. Bacterial should be allowed to remain to continue the biological process.

• Do have the tank de-sludged at least yearly.

Common Problems and Solutions

Smells / Odour

Problem, waste particles leaving the septic tank and entering the percolation area can block the exit allowing the septic tank to overflow.

Solutions: Have the tank and pipes emptied at least yearly.

System backing-up

Problem, blockage in the septic tank pipes, percolation area blocked.

Solution: Clear tank pipes. Remove and replace percolation area.

Septic Tank refilling immediately after emptying

Problem, high water table. Ground water enters into the septic tank from the percolation area.

Solution: No easy solution. (possible solution is to increase the height of the area were tank and percolation area are located-expensive and not always a solution)

Septic Tank refilling immediately after emptying

Problem, High water table: Tank cracked / damaged allowing ground water to enter the tank.

Solution: Clear and clean tank, repair or replace tank.

Differences between tanks and biocycle (secondary treatment systems).

A tank does not have any movable parts. its basically a two chamber concrete tank that uses anaerobic bacterial action to break down effluent waste.

Biocycle and other secondary treatment systems have movable parts such as maceraters, aerators etc to aerobically break down the effluent and need a source of electric power to operate.

Biocycle / secondary treatment systems have shown to breakdown a higher percentage of solid waste and have safer effluent than septic tanks as the sludge decomposes through a mechanical assisted aerobic and anaerobic process. This can be twice as efficient as a non-mechanical assisted aerobic and anaerobic process in a traditional tank.

The requirement to use a septic tank or secondary treatment system is usually dependent on the site conditions, however most Local Authorities (following a site assessment), will now require the use of a treatment system fitted by an approved contractor with appropriate professional indemnity insurance. Always check with your Local Authority before carrying out any renewal works to an existing septic tank.