Hi Hilary,
I lived in SC for nine years and loved it there. We moved back north only because of my illness and family who wanted us to live closer to them. I am also 69 and exercise everyday. I was diagnosed three years ago with both too. Water is an issue for us no matter where we live due to the mycobacteria avium complex in it. I boil my drinking water or use a Lifestraw water picture and water bottle. I also boil distilled water to use for my saline nasal rinses as distilled water can also carry the bacteria. If you live in the Charleston area, UMSC has bronchiestesis and MAC specialists. If not, be sure you go to a pulmonologist and ID doctors who know the disease well. It’s also important your other doctors know especially when you have changes or other diagnosis with your health (ie acid reflux is an issue). There are a lot of resources for us to utilize. Ive attended many seminars. Scoop, above reply, provided an excellent source where you can learn a lot. You can look there to see if there is a local support group. I would not move but I would make all the necessary changes in my life (boiling water, airway clearance etc.). Keep exercising as it’s a great airway clearance. I hope all goes well for you.