If it is properly designed and installed, and is the right size and type for the property it serves, a septic tank can be a very efficient way of dealing with sewage and waste water. However, no matter how efficient it is, any septic tank will build up some sludge over time. The only efficient way to deal with this sludge is to have the tank pumped out.
In most domestic household situations, a septic tank will require pumping out approximately every 2 to 3 years. There are some areas, though, where local ordinances require it to be done more often than this. Local contractors that provide septic tank services are usually clued in on all applicable rules and regulations, so if you are in doubt, consult one of them.
Obviously, if the tank is nearly full, it needs to be pumped out as soon as possible. If it is filling up very quickly, you should have it checked by a septic tank expert, as there may be blockage, a problem with the drain field, or another issue requiring attention.
Another possibility is that the septic tank may simply have become too small for the household’s requirements. Sometimes homes are built fairly small and then extended as a family grows, for example. In this case, the septic tank may have been sufficient in the beginning, but as the volume of waste grows and / or there are more bathrooms added to the home, it may become inadequate.
If you have to pump out your septic tank every few months, talk to a contractor with a good reputation locally about the possibility of replacing your septic tank with a bigger one, or even adding a second tank of the same size to run in tandem with the existing tank.