Don't worry, this black water (not Blackwater) isn't actually sludge -- it's just water enhanced with humic and fulvic acid (biodegration of dead organic matter, electrolytes, antioxidants, and so on). Super yum!
Blk water, according to its website, is "an innovation of Nature and Science" (why yes, that is nature with a capital "N"). It has been gaining traction among people who choose to spend money on a product that you can get for free, including an appearance in an Emmy gift bag and an endorsement by many of the Real Housewives of New Jersey. We haven't tasted this soy sauce-esque water, but it does supposedly taste like regular water.
In case you feel like jazzing up your Rosh Hashanah dinner this year, blk water is certified kosher. L'Chaim!