Combine water, pinto beans, and garlic in a large pot and cover. Cook over low heat for 5 1/2 hours. Stir in salt and continue cooking until beans are very soft, about 30 minutes more, adding more water if needed during the cook time to ensure the beans remain covered.
Heat canola oil in a skillet over high heat. Spoon the beans into the skillet without draining excess water; mash beans using a potato masher until they begin to lose their shape, about 3 minutes.