Which animals can swim up your toilet?

Insects

Bugs are drawn to water, which means you’re most likely to find them creeping around in your kitchen or bathroom. Insects can be hard to track to a source, since they may not come directly from your plumbing, but just be attracted to those areas from the moisture. Centipedes and other insects may not come from your drains but could get stuck in sink or shower drains and climb back out once the coast is clear.