Redundant colon and excessive thirst

Has anyone linked having a redundant colon with excessive thirst? I’m constantly thirsty day and night. If I eat anything substantial for dinner I wake up every few hours with a dehydration headache and have to drink 20 ounces of water. I can no longer drink alcohol because it makes me too thirsty. I’ve had MRIs, and every lab test there is and all are normal. My theory is I need a lot of water to move food through, especially after I’ve taken MiraLAX. I used to be very sensitive to caffeine and maybe that helped me in the past. Now caffeine doesn’t affect me much. I’ve had a long history of GI issues my whole life. Thanks for any insights.