Tanks not only have to be pumped but they also need to be pressure washed.
Tanks accumulate a bottom layer of sludge. This sludge layer slowly deteriorates the bottom of the tank. This causes cracks, leaks, and sinkholes overtime. Normal vacuum pumping alone will not remove this problematic sludge layer.
Now, not only does servicing a tank properly affect the tank itself, but it drastically increases the life of the most important part of the system, the drainfield.
The drainfield is the portion of the septic system that drains all the water incoming from the tank into the ground. Without a functioning drainfield, your septic tank fills and begins to backup into the home.