This is a well-established field where you can read experts discussing the word in depth, including its derivational properties and ablaut behavior. This isn't something where an HN's armchair guess is worth anything, just like when laypeople use HN threads on quantum theory for their own inane ideas.
Carl Darling Buck (A Dictionary of Selected Synonyms in the Principal Indo-European Languages) and Julius Pokorny (Indogermanisches Etymologisches Wörterbuch) are just a few of the philologists who have posited this "dead water" hypothesis