This will depend on what type of waterbed you have, so the answer is both yes and no. Regular flat sheets will work adequately on a hard-sided waterbed as long as they are snugly tucked under the mattress. Regular fitted sheets will not work on any type of waterbed because their pockets are simply not deep enough to fit around a waterbed mattress. Ultimately, it is best to use a set of waterbed sheets on your waterbed because they are designed with larger pockets and more elasticity to prevent them from sliding off. You may get away with using a larger-sized set of regular sheets, but this is not ideal.