Deka tea was a type of Bajoran beverage.
In 2346, deka tea was part of the spread laid out for Kira Nerys and Kira Meru in their quarters aboard Terok Nor. (DS9 episode: "Wrongs Darker Than Death or Night")
In 2360, iced deka tea was served to Riszen Ketauna, Opaka Sulan and the others who were landscaping the gardens of the new Kendra Shrine. (DS9 - Terok Nor novel: Dawn of the Eagles)
Deka tea was served in Quark's. In 2370, Mora Pol ordered the tea. (DS9 episode: "The Alternate")