36" wide, and this width should be adequate for containing the spray from most showerheads. However, with a handheld spray nozzle you might want a little more protection.

what color is the tile? and what are the name of the lights used? so beautiful! thank you

The tile is Ceramiche Campogialliano Strand in the Silver color. http://www.ceramichecampogalliano.it/zoom.php?idk=60 The lights are Terzani Mizu 3-Light http://www.ylighting.com/terzani-mizu-3-pendant-light.html