Under ordinary circumstances, you should be able to go at least a few years between each septic tank pumping. If you find yourself having to do that more often, and if sewage otherwise starts backing up into your house on a frequent basis, there may be something more serious that needs to be repaired.
Main Drain Clog
One possibility that doesn't necessarily point to any serious damage to your system is a clog somewhere in the main drain pipe of your septic system. This is the pipe to which all other drain pipes lead and which goes directly to your tank. A clog here, whether partial or complete, can cause sewage to back up into your house in several places, but can be so far down in the pipes it isn't immediately noticeable.
This can sometimes happen as a result of things like paper towels or other products that shouldn't be flushed, but it can also happen if roots from nearby plants or trees are starting to grow through the pipes. This kind of clogging necessitates the replacement of the affected pipes and the removal of the plants causing this damage. One way to try to narrow the cause of the problem down is to locate your drain pipe and check for nearby plant growth to see if these plants could be damaging your underground pipes.
Broken Drain Pipes
Drain pipes that have been in any way damaged can often lead to effects similar to clogging, especially if the affected pipes are underground. Underground pipes can break for several reasons, including age and wear; weight damage, such as that from vehicles driving or parking on the ground above; root damage; and shifting soil that has pushed the pipes far enough to break or disconnect.
Broken pipes sometimes exhibit detectable symptoms like puddles of water and sudden plant growth above where the break has occurred. You may also notice a foul odor in the area, usually indicative of leaking sewage below ground. This needs to be fixed immediately, as this not only causes backups into your house but can also affect soil movement and potentially damage your tank itself.
Failing Drain Field
Your drain field lets liquids absorb harmlessly into nearby soil, leaving the tank to primarily hold waste, which is what lets you go so long between pumping. If this drain field fails and can no longer drain out liquids, these liquids will instead collect in the tank. With nowhere to go, sewage will start to back up into your home much more often.
If you notice this issue despite regular pumping, and if your septic technician notices that they are removing primarily liquids each time, it is likely your drain field needs to be repaired or replaced. If you have enough space, you can sometimes have a second field installed adjacent to the first, letting you switch between them as needed in the future.
For more information, contact a septic repair service.