Cook ground beef in a large pot over medium-high heat, stirring to crumble, until evenly browned. Drain off grease.
Reduce heat to medium; add kidney beans, bell peppers, onion, and garlic to pot. Cook and stir, 1 to 3 minutes. Stir in tomato sauce and water; season with chili powder. Simmer over low heat, uncovered, for 40 minutes.