JimL wrote:

I have been using the bleach treatment on my drains for years.
The only damage is that it gradually wore off the shiny chrome
surface of the bathtub drain, and left the dull brass underneath.

Something else would have done that, not the bleach, or the
drain was very badly chromed. You dont get that effect with
kitchen sinks when you use bleach, or with laundry tubs either.

Bleach wont dissolve chrome.

No big deal to me. On the sink drains I wipe off the chrome
darin ring afterr pouring the bleach downt he drain, and careful
not to splash! (as withness the ****e spots on a blue shirt