There are 2 big differences between a septic tank and a holding tank. The first big difference is that a septic tank is one big tank with two compartments versus a holding tank which is also a big tank but everything is one giant compartment. You can easily identify which is which by looking inside. The septic tank will have a separation wall just right there where you look inside. The second big difference is that a septic tank is accompanied by a disposal field versus a Holding tank which has neither a disposal field nor a pump. Everything (Solids and liquids) flushed down the drain is captured in the holding tank and waits there for a septic tank service to pump it out and therefore needs to be pumped out a lot more often. In a septic system the solids and the liquids go into the first chamber but then the liquids flow into the second chamber where they are pumped out into the disposal field. These are the biggest differences between a septic tank and a holding tank.
Hanover Septic Tank Service 