I think you might have wet grout that does not dry due to bad draining. Did you take pics during construction? Was a slope done correctly? I had a similar issue it took a do over to fix. Good luck.

Wondering if it might be a hard water problem with respect to the discoloring. As for improper drainage, I agree with Roarah.

How do I test for hard water?

Re testing for hard water. Purchase a water test kit.

I’d have a dollar bet that someone used mastic and there is no waterproofing. They probably did a flat on the deck pan too. They contaminated the drain with either mud or thinset.

Thats a redo most likely. Pictures of it under construction with the products used would be helpful in saying for sure.

How do I get the thinset out of the drain?

Call the contractor or tiler who installed and have them fix it.

Getting the grout outta the drain ain’t gonna fix the mold from using organic based products to set the tile. Nor will it cure the bird baths and flat preslope.

Hi I want to mention that my contractor poured concrete high enough to be flush with the drain flange. The drain when it was screwed in wasn't flush. It was about 3/4inch higher. It is a square drain not like the regular drain which screws to lay on top of the tile. The instructions said to lay mortar or concrete down around the drain leaving enough room to lay the tile. However, my contractor instead cut a square hole in a piece of wonderboard and laid that on top with the drain fitting into the square hole. So there is wonderboard beneath the shower tile floor not concrete. Can that have something to do with brown stains building up?

if not properly sloped that wonder board becomes a spong that holds all the water that did not egress properly down a sloped drain. The wonder board will not fall apart but the water needs an egress so it is being wicked up to the floor corners and up into your wall grout and substrate boards and possibly your wood framing. Left long enough the brown line will continue to travel inches to feet up off the floor into walls. It is similar to putting at shirt tip in a full bowl of water. Eventually the water line travels up the cotton to areas not dipped in the bowl.

The brown spots could be just wet grout with hard water or more likely they are mold for the shower never fully dries.

It is not worth speculating what is wrong you need a pro to explore why this happened and who should pay for the fix. Call your GC and start documenting everything you can remember about the build. Pictures of that build will help fight for a refund.

It sounds like I'm going have to rip up the shower floor, tile, wonderboard and everything and have it redone properly by an experienced general contractor.

Find out how your shower walls were waterproofed. In my case it was Kerdi and all tied into the floor so it would have been compromised by removing only the floor and top row of tile so the whole thing was redone. I took pictures after every step orginally and during the redo so I have a trail of evidence if it needed to go to court.

In my state we have to give the orginal contractor the right to make it good before financial retribution. My GC asked the tiler for a full refund but the tiler opted to do it over and by law we had to let him or walk away from about 10 k. I was worried but my GC stayed on site while the same tiler redid it properly. They tore out all of the orginal shower, provided all new materials and redid it. If it still failed than I could get a full refund and pay someone else only after I had given the first tiler a chance to replace his faulty work. It seems to be right now a year later. The floor is dry within an hour or so and all grout looks the same now.

My GC, who did provide the tiler, was in my corner the whole time. I never had to fight for it to be made right I just researched and got second opinions from two other pros, one Kerdi rep and another local tiler, on what was failing and how to fix it. Tundra, and creative tile helped me with the orginal trouble shooting and tundra gave me the great advice to not settle for a partial fix on a new shower. He reminded me that I paid for a new shower not a repaired one.

i think your first step is to call your orginal GC. Explore how the shower was constructed. Look over your contract terms and get a opinion from a local contractor on what they feel is happening.

Good luck.