Food becomes unacceptable for the people to eat because unclean water has fallen on it is spoken of as if it were physically unclean. (See: [[rc://en/ta/man/translate/figs-metaphor]])
This can be translated in active form. AT: "You must break it to pieces" or "You must shatter it" (See: [[rc://en/ta/man/translate/figs-activepassive]])