We had something like this and I had gotten no further than, "Note to self: check into that" than our entire drain system stopped working. It turned out we had roots and/or bad installation that had resulted in our drain pipe being connected not to our (newish) septic tank, but just ending in the dirt. This is not good.
Is there any possibility of a stop-up in your system, either septic or sewer, that is causing water not to flow out of your drain system?
Once the severity of our problem became obvious, it was really, really obvious. But that took a couple of weeks.