What is a Septic Tank?
A Septic Tank is the main part of a septic system, essentially a very small scale sewage treatment plant. It is commonly used in properties that have no connection to the mains drainage system.
The term septic tank refers to the process inside the tank where anaerobic bacteria work on and mineralize the waste that is discharged into the tank. Septic tanks can be joined with other treatment units such as bio-filters, for example the Bio-rock, or aeration tanks such as the Tricel Biocel.
Periodic maintenance is required in order to remove solid waste from the tank, and in the UK such maintenance is required by law every year. If the maintenance is neglected then the septic tank not only could fail, but the Environment Agency could prosecute if a septic tank is causing pollution. Properly maintained, a septic system can last for a very long time.
Septic tanks come in many different sizes but domestic tanks generaly like this: 2800-3000, 3600-4000 and 4600-5000 litres; one side of the tank should be connected to the waste pipe of the property and the other end to the drainage field or soak-away. A septic tank should have a T- pipe on the inlet and the outlet so that no solid waste enters the drainage field.
Most septic tanks have two or three chambers, apart from many of the modern cylindrical filter type septic tanks and the Klargester onion shape septic tank that has a curved inlet and outlet pipe.
The Process: Waste enters the first chamber, this allows solids to settle and the scum to float to the surface forming a crust, the settled solids are then anaerobically digested, whereby the volume of the solid waste is reduced. The remaining liquid waste will flow to the second and third chamber and further settlement of the waste can take place. Finally the excess water can flow out of the outlet to the drainage field for further treatment from the soil.
Another variation of septic tank is the two tank system, the benefit of this system is that the solid waste remains completely separate from the liquid waste and treatment is therefore normally to a higher standard, but in most cases the two compartment septic tank is sufficient for the job.
As already mentioned, the remaining solid waste that does not break down in the septic tank must be removed by law once a year, and it makes sense to adhere to these guidelines since should solid waste enter the soak-away or drainage field, the septic tank could fail and this would be costly to repair.
Septic tanks that are well maintained should be odour free - if you are getting nasty smells from your septic tank then it is probably in need of some attention. For free, impartial advice or information please contact UK Septic Tanks on 01296 326111.