Kathy - Both my pulmonologist and my ID doc keep stressing that MAC is EVERYWHERE. That there is no way to completely avoid it short of living in a sterile bubble. Just be sensible & don't inhale the water. I can't even tell you "just shower afterwards" - it could just as easily be in the tap water.
Another friend was told to stay out of her yard because MAC was there - I asked her what air she breathed in her house and car? Same ID doc told me I can even garden, just wear gloves and also an N95 mask if handling potting soil or mulch, or if it's dusty where I'm working. Remove clothes and shower afterward. I have been doing that for years anyway because I have dust and pollen allergies. Just means a little more laundry as I wash the garden clothes & gloves every time I wear them, instead of waiting until they are really filthy like I used to... Also, if wearing an N95 mask, remember it is only effective for 4-6 hours, depending on what you read, or until you get it wet.