We recently finished construction of a new home. In two of the showers, the grout lines in the tiled shower floors are continually black (white was the original color). This happened immediately. Thinking it was dirt we tried to clean the floors with aggressive acidic cleaners with no success. Not all of the grout lines are totally black. Some are grey. The grout was not sealed and we tried to clean the tile in order to seal it. We have waited up to two weeks to see if it was water darkening the grout and to see if it would dry.

We have been told it is water under the tile that is not draining properly. Some say that water which is sitting under the tile is not normal, others have told us that the shower pan is doing its job by holding the water. What could this be and if it is water, shouldn't it drain within a reasonable amount of time? Also, the water appears to be wicking up the lower grout lines in the shower walls.

If this is water that is not draining, what is the solution to this so that we can have our original white grout and then seal it? I am afraid of mildew in the near future. (The tile setter was supposed to seal it!)

Thanks for any help!

You apparently have many friends who are clueless regarding tile. There is, or should be no water at all under the tile. How much time has passed, call the tile man back and ask him what is happening and how he will fix it. MKol;d and dirt do not build up this fast.

ballengerb1 was bang on with his answer. The tile grout should have been sealed at the time of installation. The flange type shower drain,(see image) has weep holes to allow excess water to drain away if it seeps down into the shower pan. Some times a careless tile man will allow mortar to block the weep holes. This is unacceptable and should be corrected at no cost to you. You should have a years warranty on your new home, call the contractor/builder back and demand both problems be repaired under the terms of the warranty. Let us know how you make out. Good luck, Tom

For hundreds of years no one sealed grout in a shower, now if it is not sealed you got to rip out the tile. I disagree.
Grout does not stop water, it is like a sponge, water goes right through. That is why weep holes are in the shower drain. Water always is in the pan under the tile, always has been. That is why a pan is required.

Speedball as usual is right. I had a shower, where the weepholes under the tile were blocked. Water collected in pan, stagnated and started smelling. Unhealthy.
Think of tile and grout as water resistant - pan has to do it's job if/when water gets into it.
To add to my trouble, my shower had gypsom board resting in the pan. Water wicked up and disintigrated the walls and tiles fell off. New shower had only five years before failing.
Other plumbing and tile installations are still good after 100 years plus - the difference is in doing the job right - get them back to do it correctly !