Keep it simple: only human waste and toilet paper go down the toilet. Everything else is a risk. That means no “flushable” wipes (they’re not actually flushable), feminine products, diapers, paper towels, cat litter, or medications. In your sinks, avoid pouring grease, oil, coffee grounds, or harsh chemicals down the drain. These things don’t break down easily and can clog your system or kill the bacteria that help decompose waste. When in doubt, throw it out—your cesspool will thank you.