Live in small town MN. Can my old landlord come to my new rental home to chastise me about a city water bill?

Old landlord showed up at my door this afternoon saying I needed to pay on an outstanding water bill. I have been making small payments to the city I used to live in. I did not give this address to my old landlord. I do not owe the landlord money for the water bill; I owe the city. I'm concerned that came over unannounced and uninvited. He says he will be back