Combine tomatoes, onion, celery, water, tomato sauce, 1 teaspoon salt, and 1/4 teaspoon black pepper in a large saucepan; bring to a boil. Reduce heat and simmer until onion is tender, 10 to 15 minutes.
Combine remaining 1 teaspoon salt, 1/4 teaspoon black pepper, brown rice, and basil in a bowl. Fill green bell peppers with rice mixture. Carefully place peppers in the tomato sauce mixture, spooning some sauce over tops of peppers.
Cover saucepan and simmer until peppers are tender, 40 to 45 minutes.
