@yardsend I haven't seen any research on that

@yardsend For anyone interested, I've been emailing with Dr Joe Falkinham, a microbiologist at Virginia Tech. He has done lots of research with NTM. I asked him about UV light as I know nothing about it. Here is what he said

"UV-light can sterilize water, if the UV-lamp is sufficiently powerful and any water and cells is exposed for a sufficient time to kill the NTM. Further, the use of UV is limited as it only kills cells that are directly illuminated. NTM on the walls of pipe away from direct exposure to the UV will not be killed. Finally, cells of bacteria, including the NTM, have an enzymatic system that repairs UV damage, reviving the cells from dead to living.

I am not a fan of UV use in households."