Your septic tank consists of several parts, each with its own purpose and maintenance needs. Knowing the parts of your system and how they are most likely to fail can help you properly schedule maintenance and avoid problems. Generally, the septic system should be inspected annually.
The entrance of the sewage from your home into the tank system begins at the input baffle. The baffle connects the main sewer pipe to the tank, below the soil surface but near the top of the tank. The main maintenance concerns at the input baffle involve clogs and leaks. Since the baffle curves into the tank, a clog can sometimes occur and cause sewage backup in the home. Increasing baffle size and taking care to avoid flushing items like diapers minimizes this. Leaks occur when the seal at the tank and baffle connection fails, which will require a repair.
Most septic systems consist of two holding tanks connected by a pipe. Generally, these are single tanks with a divider that makes them operate as two tanks. The majority of the sludge settles to the bottom of the first tank so that the clear effluent rises to the top and flows through the pipe in the second tank. Any remaining sludge in the effluent then settles out in the second tank, so that it doesn't clog the drain field. Holding tanks have a lifespan of decades, but they will need to have the sludge pumped out periodically, as the bacteria in the tank can only process so much.
The output baffle connects the second tank to the drain field. Clogs are not very common at this location, since primarily clear effluent passes through. Generally, the only issue to worry about at the output baffle is a small leak, which can usually be repaired by replacing the outlet valve or a gasket.
Most septic tanks have three access points — a central manhole in the event a service tech must enter the tank, and a small inspection port above each tank so that sludge levels can be monitored. Make sure tank lids are kept in good condition and that landscaping is trimmed back so access doesn't become blocked. The gasket that seals the access lids against external moisture may also require periodic replacement.
Contact a septic tank service if you have more questions about how the system works and needs to be maintained.