I Am A Therapist, And Have A 10 Year Old

I am a therapist, and have a 10 year old boy, who is not disabled, that constantly drinks water from the toilet at home and school. It is affecting his health as he gets cold sores, and has even gotten sick after drinking the chemicals used to clean the toilet. I have only seen the child once, so far, but am concerned about how he could be affected, and thought that maybe if there were pictures or something to use to deter this negative attention seeking behavior.