On Jul 11, 11:19 am, wrote:
The lowest course of wall tile at the rear of the shower won't dry
out with daily use and is dark.

This is a newly constructed mud shower pan and enclosure. There is
12x12 marble tile on the shower walls, and 2x2 marble on the shower
floor. The marble has been sealed, the drain weep holes open, pre-pour
mud/liner- sloped well etc.
It seems that its getting wet fromt the back.

Is this a construction problem in addtition to aesthetic?

Thanks!

try bleach to see if its mold