Advice Needed: Slow Emptying Toilets & Septic Tank System

Sounds to me like the problem lies with the way the toilets were set. If it is emptying into some sort of anything other than being directly connected to the waste pipe, then don't expect it to flush like one that is. When you do have to finally disassemble it all, probably due to compaction or whatever...you will need to get the discharge pipe extended to where you can connect to it properly. In the real world, you don't just dump crap into a basin that is connected to the sewer and expect the flushing water from the toilet to properly work, flushing out the solid waste on down the line. pg