I recently had my septic tank pumped, so I don’t understand how it is full already!
First you must understand that every time a gallon of waste enters the septic tank a gallon of liquid called effluent leaves the septic tank. The septic tank is designed to hold the solids. There are 3 layers of a septic tank. Top layer is a foamy, scummy, grease layer. The middle layer is effluent (liquid) layer. This is the layer where the break down process occurs. The bottom layer is the solids. As solids build up in the bottom of the tank it leaves less and less room for the liquid layer to do its job of processing and breaking down the waste. So, if you remove the lid of your septic tank and look in it, it is always going to look full, as the level in the tank should be at the bottom of the inlet pipe and the outlet pipe. Should the level be higher than this, it is time to be concerned and get the problem evaluated.
A tank should be pumped when the solids are a third full. The length of time between pump outs has too many variables to give exact times. Some of those variables include how many people are living in the household, the size of the tank, and does the household use a garbage disposal?