Is "Έχει νερό πάνω στο πάτωμα" also correct?
it is correct although it is obvious that it is "πάνω" (on) the floor, so you do not have to say it
Thank you. I also wanted to know if I can use 'έχει' instead of 'υπάρχει'.
i am not sure in terms of grammar, but in common speech "έχει" is used 99,9 % of the time rather than "υπάρχει".