my son woke me one morning by holding a small green snake at eye level. ' hey, mom, i found this in the toilet. can i keep it?' can't believe i said yes. i don't make the best decisions when awakened rudely. lol. he got bored with it in a few days and released it outside. we had a vast number of varmint short term visitors. the tarantula we found in the backyard, and brought in, lived in a tank for about a year. after it molted my son let it go. my husband taught biology and that just led to our kids observing and honoring animal life. not everything came into the house, and only that one snake came through the toilet! people with inground pools often find animals swimming or drowned. the chlorine kills them. but ducks, frogs, squirrels, birds, snakes, possum, raccoons, etc. all will be attracted to water and those too young , old or sick will be unable to get out.