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Introducing non-biodegradable or harmful substances into the septic system can severely disrupt its natural biological processes and lead to costly failures. For instance, if the internal T-baffle (which directs flow and retains scum) were absent, the floating scum layer (composed of grease, non-biodegradable wipes, etc.) would flow directly into the perforated pipes of the leaching field, quickly clogging them and preventing proper drainage. Similarly, chemicals like paint or excessive amounts of solid materials like kitty litter (made of clay) and coffee grounds can kill the beneficial bacteria in the septic tank, halting the essential decomposition process. When the system's ability to process waste is compromised, the tank fills up, causing sewage to back up into the house, and necessitating expensive professional pumping and cleaning.