Since a septic tank depends on enzymes and bacteria to break down organic waste, there are a number of industrial and household products that you must avoid flushing down the toilet. These include antibacterial products, cat litter, cigarette butts, cosmetic products, expired medicine, dental floss, latex condoms, paper towel, plastic, sanitary napkins, toilet paper and wet wipes, among others.
Besides harming the bacteria, these products can damage the septic tank and cost you a fortune in repairs. If you have guests or rent out your property, it is a good idea to post a notice to this effect in your bathrooms.