Solids don’t fall out of solution. They could, however, fall out of suspension.
We just had a similar occurrence. We need to have our sewer line cleaned out at least once every two years.
Beg Pardon; should have said suspension, just getting old I guess.
Particles in solution have basically become one with the water, and will continue with the flow.
Particles in suspension will fall out of the water due to their specific gravity, the particles being slightly denser than the water.
I appreciate your correction.