This.
Mycobacteria can't survive conditions higher than 3% salinity. That's why sea/ocean water (which is 3% saline) is 'safe' from a re-infection risk perspective. Swimming pools, spas, etc. are high risk due to low salinity of the water.
At NJH, they go from 3% all the way up to 10%. I use 7%, which took some getting used to, but I'm convinced it's what dramatically reduced my colony count from over 200 to 3. 17% of people who neb with saline are able to convert to negative.