Flushable cat litters are more biodegradable than clay- or silica-based litters, but they can still pose a hazard when flushed into a septic system. The dry cat feces itself can still clog pipes and can also carry dangerous contaminants. Manufacturers recommend flushing “flushable” cat litter in small batches to avoid blocking the pipes leading to the septic tank, and the litter may not break down completely in the septic tank like paper-based products.