Most septic problems start quiet
A septic tank doesn't usually fail with a bang. It fails with a slow drain you've been ignoring for a month, or a soft wet spot in the yard you figured was just a bad sprinkler.
By the time sewage backs up into the house, the tank or the drain field has usually been struggling for weeks. Catching it early is almost always cheaper and a lot less messy than waiting for the obvious sign.
That's the whole point of the free checker on this page. It walks through the same early warning signs a pro would ask about, so you know whether to call today, call soon, or just mark your calendar.