Septic tanks work by allowing waste to separate into three layers: solids, effluent and scum (see illustration above). The solids settle to the bottom, where microorganisms decompose them. The scum, composed of waste that's lighter than water, floats on top.
How do you build a low cost septic system?
The cheapest way to build a septic system is by using a heavy-duty IBC tank or recycled barrels. These materials are more inexpensive than concrete and don't require hiring professionals to help with installation. Besides, using either method is faster than building using concrete or steel.
What is the least expensive septic system?
An anaerobic or conventional septic system costs $3,500 to install on average with most homeowners paying between $2,500 and $5,000. These are generally the quickest, easiest, and cheapest to install, and the effluent travels through the septic tank and on into the drain field using gravity.