Poor prep means that exists until you tear it out and fix it. Your BIL should not have moved forward with tiling until the prep work was dead nuts right.

You havent done enough of the rest to not tear that floor out and redo it. Tear it out. How many times pros have ripped it all up and redone it when it wasn’t right is one of the big things that makes for a successful pro who learned from their mistakes. Learn ftom your mistakes, and get it right. Now. Do not live with that mistake.

Hire someone other than your BIL for tile install. He is not a qualified tiler.

He did it for us for free, so if anyone is tearing it out, it will be us. Can we tear out the tile without tearing up the pan? If that is not possible, we will choose to just mop up all water off the floor after every shower (this isn't our forever home) because we aren't willing to spend another >$1000 on a new pan, joint sealant, and tile.

How did your 48hr flood test go. ?

We flood tested the pan for 72 hours before the tile install. It went fabulous. No leaks whatsoever. We repeated the test just to be sure - same result. So the shower itself is great. It's just the tile that's an issue.

Great to hear show me some photos of that process. specifically the type plug used and placement of the plug.

We didn't take pictures, but we know the drain system and the pan is perfect because it wasn't the first test we did (out of three tests). In the first test, the drain wasn't tightened down enough and all 8 gallons of water funneled from 2 points in that flange into our dining room ceiling. We cut out all the sheetrock and left the ceiling open until we got the drain clamped tight and the water, filling all 4 corners to the top of the curb, held without a hint of leak for 72 hours, then we repeated the test again to be sure. (Only then did we repair the ceiling.) We used a foam bulb shaped drain plug made and provided by Hydroblok just for the purpose of the flood test. We followed Hydroblok's directions: "The supplied screw hook can be screwed into the Foam Test Ball to act as a handle for inserting and removing the ball from the drain opening. DO NOT insert the supplied Foam Test Ball more than half way into the drain pipe without using the supplied screw hook or it may be difficult to remove."

Can we do another drain test right now with mortar and tile laid (no grout) just to see how much water pools or how quickly it evaporates?

The issue there is the test plug needs be inserted down into the drain pipe BELOW pans drain or youve not truly tested the drain to supplied drain connection.

I would go get the proper Cherne test plug. Infllateable and insert it below the drain down below the supplied drains flange and riser. to just above the bend in the trap. Now your testing the drain and the pan properly..

very common mistake when flood testing !

Once you have the inflateable plug inflated to 40psi. You then should flood test again w pan full up to and overspilling onto curb..

Being a foam pan and assuming youve used the proper glass rated thinset mortar you should have no issues filling it up at this late stage.

Had you got the required permits (if youre state city requires flood testing) and had an inspected flood test the plumbing inspector likely would have not passed this. regardless hydroblocks instructions.

in short you need to get well below the green rubber connector into the vertical 2"

Another idea: drill tiny weep holes leading into the drain???

Thank you Mint tile Minneapolis. I am going to thoroughly go over all this with my hubby, and we WILL do the flood test as you stated!!!! No harm in hurting any DIY ego, lol. If it exists, it needs to be removed.

This site doesn't have kind people on it. I knew the response would be repugnance (perhaps toward all DIYers?), but was hoping for something more. I was the one who made the drill suggestion, and I was not the one who did the work or will be doing any of the work, so why must I have a full understanding of the how and why of something I will never be doing? I was just brainstorming, and I guess in your eyes, that makes me a fool. I asked in innocence, hoping for an answer. Not everyone is well versed in everything, thus we ask the pros, but if that means a punch in the gut, no thanks. Blessings to each of you anyway.