Flushable cat litter is a filler for cat litter boxes that is supposedly safe to flush down the toilet. However, some flushable cat litters are not safe for septic systems. Most cat litters, even the ones labeled as "flushable," are designed to absorb moisture and can easily clog plumbing.
It is illegal in some states, such as California, to flush cat waste down the toilet due to environmental concerns. Cats carry a parasite that can infect marine mammals if it is washed out to sea, as after being flushed or disposed of where it can wash into drains.
Cat litter is made out of either clay, silica or biodegradable substances. Biodegradable litter is made from plant products or recycled newspapers. Most litters sold as "flushable" are made out of biodegradable substances.