Legal Question in Criminal Law in California

You could have gone to the police but it is questionable if they would have done anything; you would have a successful lawsuit. By the way, the water in the toilet bowl is the same as what you drink from the kitchen, etc. So if the bowl itself is clean, ther would be no likely injury. But you should read the riot act to your roommate and ask them if they can legally be held to the rental contaract since they are obviously well below the age of 18.