Does the poo and pee get soggy when it goes into a septic tank?

Septic tanks usually have several run off tanks in which liquid waste runs into then drains down into the ground through rock and gravel "filters" the solid waste then fills up the tank and is usually the same consistence of mud. Once a year (depending on the usage and size of tank...) the septic tank needs to be cleaned out. A big truck with a Vacumm on the back along with quite a nasty smell. Makes you think twice before playing in the mud...