Where does “nước phèn” come from?

nước phèn (Vietnamese) comes from Vietnamese nước, from Proto-Vietic ɗaːk, from Proto-Mon-Khmer ɗaak — water; liquid; The sense of "river, stream" that...

nước phèn (Vietnamese): water with a high concentration of alum

Definitions

water with a high concentration of alum

Ancestry of “nước phèn”, step by step

nước phèn traces back through two separate lines of ancestry.

via Vietnamese nước

Step	Language	Word	Meaning
1	Vietnamese	nước	water; liquid; fluid; the liquid part of a broth
2	Proto-Vietic	ɗaːk	water, liquid
3	Proto-Mon-Khmer	ɗaak	water; liquid; The sense of "river, stream" that...

via Vietnamese phèn

Step	Language	Word	Meaning
1	Vietnamese	phèn	alum
2	Chinese	礬	—

Every word from Proto-Mon-Khmer ɗaak →Every word from Proto-Vietic ɗaːk →Every word from Vietnamese nước →