What is the ruling on praying in a mosque built on a canal that runs through the middle of a village and into which some impurities are cast?

Prayer in this mosque is valid and there is no harm in it, whether the canal flows beneath it or not, and whether its water is ritually impure or not. This is based on the saying of the Prophet, peace and blessings be upon him: "The entire earth has been made a place of prayer for me and a means of purification."