What you put into the Municipal sewer system and your own septic greatly affects its ability to do its job. As a general rule do not dispose of anything in the system that can just as easily be put in the trash. Remember that the system is not designed to be a garbage disposal.
In the kitchen avoid washing food scraps, coffee grinds and other food items down the drain, including grease and cooking oils. In the bathroom don't use the toilet to dispose of flushable wipes, plastics, paper towels, tampons, diapers, condoms, kitty litter, etc. These items can overtake an destroy the biological digestion taking place within the system and cost you money in the long run. The only things that should be flushed are wastewater and toilet tissue. Please refer to the "Do Not Flush" list below: