Does all standing water on tiles become impure by a drop of blood falling into it, knowing that it is less than two qullas? And do walls that have been painted over dry blood become impure, and does the paint that touched the dry blood become impure?

You may be afflicted with waswasah (whispers of Satan leading to obsessive thoughts), so beware of it. Water into which blood falls becomes impure if its state changes; otherwise, it is ruled to be pure. Some scholars hold the view that impurity does not transfer from one body to another, even if it is wet. There is no harm in using leftover paint unless it is known that an impurity has fallen into it, and many scholars permit the use of an impure substance for purposes other than human consumption and outside the mosque.