Water coming up from under stone tiles
Is this adjacent to a restroom , laundry room , is there a restroom above, the wall adjacent to the tiles , is it a wet wall ( is called like that when all pipes are running on a wall) if it is a wet wall maybe a pipe could be leaking, you will say how ( pipes touching other metals inside the wall they rub against each other and make a hole small one it happened  to me, to much explanation .
See the plans of the house if you have them.
Also the water could be sipping from outside? check that too.