Bring water and salt to a boil in a large saucepan; gradually stir in grits. Reduce heat; simmer 30 minutes or until thick and tender, stirring frequently.
Remove from heat; stir in cheeses, pepper sauce, and white pepper. Cover.
Melt butter in a large nonstick skillet over medium-high heat. Add corn; sauté 4 minutes or until lightly browned. Add corn and green onions to grits mixture, stirring well.