Combine water and broth in a saucepan and warm over medium-low heat.
Melt butter in a large nonstick saucepan over medium heat and add olive oil. Add onion and saute for about 3 minutes, or until softened and translucent. Add rice; cook 2 minutes, uncovered, stirring constantly. Stir in wine and cook 30 seconds or until the liquid is nearly absorbed, stirring constantly. Add 1/2 teaspoon salt to the risotto.
Add broth mixture, 1/2 cup at a time, stirring constantly until each portion of broth mixture is absorbed before adding the next (about 20 minutes total) until broth is gone or rice is cooked through. About 10 minutes in, stir in the corn. Once the rice is done, remove from heat and stir in cheddar.