You're sure it's not a change in lighting?

Yes, I'm quite sure. I've looked at this floor a hundred times a day, every day, for 7 years - in all types of natural and artificial light. They were fine when I went to bed last night. All of a sudden, this morning, 5 tiles whole tiles are blue gray. All the others are ivory. Picture doesn't accurately show the marked contrast, the darkness of the affected tiles. I'm going to call the tile store where it was purchased. BTW, the tiled area is extensive - kitchen, living room, and hallway

Thanks. I just got off the phone with tile store - that's exactly what he said.

Is that a refrigerator that I see in the upper right corner? Does it have a water-ice machine? If it does, it is most likely the source of your leak.

My husband has just disconnected it, also suspecting it. But on the other side of the counter, to the right of the sink, he spotted some water under the dishwasher, which we used only once a couple of months ago -- after our new cabinets and countertops were installed. We will eventually locate the exact source of the leak, but the thought of pulling out 2-month- old cabinets, new quartz countertop, and sink - to remove the affected tiles and (hopefully) prevent mold- is pretty upsetting, though we likely don't have a choice.

Any suggestions? And thanks for taking the time to respond

Get a plumber in to do everything disconnected. Do you have house insurance? It might be necessary to use insurance if it is more than just a few hundred dollars worth of work.

Hi Grace. Would you be able to let us know how you got on? I am worried I have a very similar issue at my house now.... Thank you

Shortly after this happened, we went back north for 6 months. When we returned, the tiles were back to their original color! BUT ... yesterday 2 other tiles - in a different area - turned blue-grey. There is no possibility of a water leak in this area. I have no idea why this is happening!

Hi, I know you posted this a while ago, I just saw this and I am having the same problem. 6 to 8 tile have suddenly turned blue/gray when my tile is beige/white in color. I’m just wondering what you found out with your tile? My tile has been down for 18 years. I’m at a loss.

Cheri: our friend who installed our tile floors says that, aside from a water leak (such as from a refrigerator ice maker), the only explanation he can come up with is hydrostatic pressure. Basically, the water table under my house rose so high that, through tiny cracks in the concrete under flooring, water was forced upward into the biscuit (underside) of the tile. When the biscuit got wet, it turned blue. The blue tiles in the kitchen have since returned to original color (dried out?), but other sections later turned blue - some in another room that has different tile than in the rest of the house. We live in SWFL (lots of heavy summer rains), and elevation is very low.