The existence of various grades of a commodity says nothing about whether that commodity at those grades is fungible. Mostly it implies the opposite, in fact.
But you can't then say unqualified that "water is fungible". Sewer water is not fungible with potable water. Greywater is not fungible with distilled or RO water. I'm not convinced that sewer water is fungible at all, considering its unknown content!
AStonesThrow|11 months ago
samatman|11 months ago
The grading is assumed.