Does anyone know the history of Minoans and have proof that they were the first culture with plumbing?

Okay so my boyfriends and i were having a debate about his knowledge of history because he wanted to be a history teacher but failed out, anyway he said that because i only had high school knowledge i was wrong so some one who can find a credited sight please tell me, IS the MINOAN society the first to have plumbing, because obviously my history book is wrong???