Surface to Depth Ratio


		Surface to Depth Ratio
	Although the biological decomposition process in a septic tank is primarily anaerobic (with oxygen) there is some aerobic digestion that can and will take place if oxygen is available. You rarely see it as a specification, but in some strict jurisdictions you will see a requirement of 6 square feet of surface area for each 1 foot of depth. This is difficult to achieve for a small spherical tank that is 9/10 ths full for typical septic duty. The smallest Turtle Tank (3000 litre) does meet this requirement with 6.2 sq ft of surface area for each foot of depth.