- Combine 8 cups water, beans and salt in heavy large pot or Dutch oven. Simmer uncovered until beans are almost tender, about 30 minutes. Drain.
- Saute bacon in same pot over medium heat until crisp, about 6 minutes. Transfer bacon to paper towel-lined plate.
- Add onion and saute over medium-high heat until tender, about 5 minutes.
- Add 1 cup water, maple syrup, ketchup, vinegar, drained beans and reserved bacon. Simmer uncovered until mixture thickens slightly, stirring occasionally, about 30 minutes. Season beans to taste with salt and pepper.
- DO-AHEAD TIP:Beans can be made 2 days ahead. Cool. Cover and refrigerate. Rewarm before serving.