TT #201 · Parshas Shemini · Aliyah 7 · Passuk 34
Chabad.org — Vayikra Chapter 11 with Rashi
English: “Upon which water comes”: the rule includes water that fell upon the food by itself, not only water deliberately poured upon it.
Toras Kohanim.
Sefaria — Sifra (Toras Kohanim), Shemini
Textual inclusion — The Chazal derives the stated rule directly from the wording of the verse.
Water reaching the food naturally is included.