The disease would have to be transmitted via urine, then it would have to survive in mostly clean water for what... days? Months? Years? and then it would have to be effective after normal consumption. I'm not aware of any disease that would be transmitted this way.
There are occasionally outbreaks associated with municipal water supplies. I remember a big one from Milwaukee in the early '90s, looking it up, it was caused by a protozoa, cryptosporidium. They can be pretty durable:
