Heat the oven to 250°F and line a large rimmed sheet pan with parchment paper.
In a large bowl, whisk the egg white, water, and vanilla until very frothy, about 1 minute.
Add the pecans and stir until every nut is coated.
In a small bowl, mix the sugar, cinnamon, and salt. Sprinkle it over the pecans and stir until evenly coated.
Spread the pecans in a single layer on the sheet pan. Bake for 1 hour, stirring every 15 minutes, until the coating is dry and the pecans are fragrant.
Let the pecans cool completely on the pan. They crisp up as they cool. Break apart any clumps and store airtight.