Nearly one-third of pet owners are unaware that their pets' toys collect dirt, yeast, bacteria and mold, according to a Petco survey Wednesday. Even more alarming - one out of five pet owners wait at least a month before cleaning their animals' eating or drinking bowls, which are some of the dirtiest items in American homes. "Pets shouldn't be overlooked in spring cleaning. For pet parents, cleaning their pet's belongings may be obvious, but the importance of replacing other items may not be," said Whitney Miller, Director of Veterinary Medicine for Petco. The survey found that one in five pet owners don't know how often they're supposed to replace their pets' toys, bedding or litter boxes. Here's a simple guide for keeping your pets' items clean: Pet bowls A study by National Safety Federation found that pet bowls are some of the dirtiest items in American homes. It's recommended to wash them each day with hot, soapy water. Bedding Rotate pet bedding once a week to rid your home of the dirt, bacteria and allergens that dogs and cats bring inside. Toys Toys should be thrown away once they've become torn or ripped, and frequently-used chew toys should be cleaned with hot, soapy water once a week. Litter boxes Replace litter boxes once a year, and scoop it at least once or twice per day.