“Mayim Chayim Mey Raglayim” was an old joke about the color, (purported) quality and (purported) taste of Mayim Chayim soda. As I said, it is actually a fine product. In the 80’s the actual manufacturer was Hoffman which was a very respected local and private label producer. I don’t know who the manufacturer is today.
The other old line was to call it Chayim’s Mayim (and the other haimish brand Ber’s Mayim).