advice on septic tank maintenance, repair, installation and emptying in Essex
Brick built septic tanks are by far the most common of all tank systems found in the UK, there are however many variations on the basic principle of waste treatment.
The type of septic tank you will have will be dependant on your location, the ground type in that area and what regulations were in place, if any when the tank was installed
Basic Septic Tank Treatment Methodology
A septic tank system would normally comprise of one/two/three chambers which allow the solids in the waste water to separate, the solids either float to the surface or settle at the bottom of the chamber/s whilst the micro-organisms do their thing. Most of the solids in suspension are composed of nitrogen, carbon, oxygen and hydrogen, the bacteria liquify parts of the suspended matter and release the remainder as a gas such as nitrogen, carbon dioxide and methane.
The remaining waste water would then either run directly to a river or brook (obviously not acceptable today) or to a soak-away or leach field. Many septic tanks have a filtration tank where the waste water filters through a media such as furnace clinker, hard coal, coke breeze and broken granite before leaving the system.
How Septic Tanks Work
The image to the right shows a basic two chamber brick built tank, it is essential that barriers or baffles prevent solids and waste from passing through the system and into the outfall. In this case Dip Pipes and a H Pipe are used to isolate each chamber.
The waste water enters the 1st holding chamber through a dip pipe, the lighter waste floats to the top of the water and the heavier matter settles at the base of the tank. Waste water then has to pass up through the H Pipes and into the 2nd chamber where the process is repeated so as to allow any remaining matter to separate before the water leaves the tank system through the final dip pipe.
Septic Tank Filtration System
The above systems separate the solid waste from the water but often in an attempt to clean the waste water further a filter system would be installed in the final chamber.
The waste water passing through the filter bed is cleaned further before finding the outlet pipe and running to its final outfall or soak-away, the fine particles of waste remaining in the filter media are again dealt with by micro-organisms.
A well installed filter bed will have a filtration sheet on top of it to ensure that the waste water passes evenly through the media
more on filter systems here..........
Why Brick Built Septic Tanks Fail
There are many reasons why these tanks fail and they are mostly down to poor maintenance, you can read more here.......