A sliding barn door would be fairly rare, but sliding glass doors (framed) have been around forever. The extent of any water leakage would be a factor of the size of your shower. How long, from wall to wall, and how wide? And where would the door fall relative to your standing positions? Imagine waving your arms around a bit and the trajectory of the water.

Not sure if you've already built your project, but you might consider doing double doors and then you'd only need half your opening width in wall space to the side the door will slide.

Aside from the fact that your rough opening may be manipulated to accommodate a barn door, does the overall style of your home support this door style? Since the show Fixer Upper, I feel like there is a barn door epidemic that really does not relate well to most homes and looks strange and out of place. Aside from the function question, I think the style question also needs to be raised for your space in order to ensure your home remains cohesive as well as functional.

Mindy,,,I have both (actually 3,,,,i did a slider across my master closet). I never close this door. or the water closet doors. we just aren't in there at the same time. husband works nights, so it's not an issue in the morning. I did a pocket door w/one lite, frosted, for the entry door (this would be the best option if you can squeeze in a pocket door. looking out of the door across to my master closet:I found an old door on craigslist, painted it and mirrored the glass. door hardware and slider hardware, eBay,,,$60. for the water closet I found some raw wood, solid doors, painted them and added glass. used antique hardware and the slider from eBay. If I told you how much I paid for all of this you wouldn't believe me,,,but I could sell them for well over 1K. and the one or two times these were closed, they offered plenty of privacy. these are thick wood doors w/heavy glass inserts, and it fits pretty close to the wall.