I don't think that Home Depot is going to tell you about specifics like MAC. Costco has one also. We had ours tested but they test for thinks like Clorine, and other common chemicals. We actually had the county water guy come out and check our shower heads and the bathroom and kitchen water. But when you start questioning these folks they have no idea what you are talking about. Never heard of MAC or any other type of NTM. There again, he was testing for common contaminates and chemicals. The county will tell you your water is fine and places like Costco and Home Depot just want to sell you a water filtration system. They run anywhere from 950 to 3000.00. When I researched the only thing that I found that would kill every contaminate was a heat lamp type bulb that was somehow fixed in your water heater I think. Can't remember but it was only used for hospital and lab type commercial settings and cost 25, 000. So needless to say that is out. The second time my dr asked me if I had a shower filter, I went and got one. $35.00 at Amazon. Have no idea if it works or not but the water sure does lather better. I just asked my daughter which one to get , she has had water filters on all of her showers and drinking water for the last 20 years. Only eats organic, drinks only UV filtered water and will not buy a home near any fracking. I think that she is/was ahead of her time. I also started cracking my shower door when showering about 6 inches open. I lay a towel at the bottom of the door and point the shower head a tad bit the opposite the door. It does cut down on the steam in the shower. Open the window in the bathroom as well and hopefully some of the steam will head on out. Also have a vent above the shower that helps with the mist rising.