I was in a debate with someone about some religious topics. And one of them was a religious treatment ritual that included taking someone else's saliva and throwing water on his back then mixing both (the washing water and the saliva), then the person to treat should bathe using this water.
I insisted that this is wrong and it can transfer diseases, but my friend was not convinced.
Am I right? Are there any bacteria or viruses that can be transferred through washing water or saliva? Note that the treated person doesn't drink that. He just uses it to wash his body.