@thielmann1 Hi there, I requested my local water company to test my water several years ago for mac. They had no idea what I was talking about, but was interested in learning about it. I shared all that I knew and they sent a man out to my house with sterilized containers and got water samples from my shower, kitchen sink, and outdoor hose bib. The results came back negative. I figured that it may be case as I do get the pink slime around the bathroom drains if not diligent with cleaning. I also have not gotten re-infected with mac since moving here. The aforementioned pink slime is a type of water borne bacteria that does not allow mac to grow, If your water company refuses to test your water, there is a company that does specifically test for mac.