1. In a large pot, cook bacon over medium heat until crisp. Remove bacon, crumble, and set aside. Leave the bacon drippings in the pot.
2. Add onions to the pot and cook until tender. Stir in potatoes and water, and bring to a boil. Cook until potatoes are tender, about 10 minutes.
3. In a separate saucepan, melt butter over medium heat. Stir in flour until smooth. Gradually whisk in half-and-half cream. Cook and stir until thickened.
4. Stir the cream mixture into the pot with potatoes. Add clams, salt, and pepper. Heat through, but do not boil. Garnish with crumbled bacon before serving.