Bring water to a boil in a medium saucepan, and stir in the rice. Reduce heat, cover, and simmer for 20 minutes.
Heat oil in a separate medium saucepan over medium heat. Stir in onion, red bell pepper, and garlic, and cook until tender. Mix in tomatoes and zucchini, and season with oregano, salt, and pepper. Reduce heat, cover, and simmer 20 minutes, stirring occasionally.
Stir cannellini beans into the tomato and zucchini mixture, and continue cooking about 10 minutes. Serve over the cooked rice.
