I have wondered about this too. I am scrupulous and my holy water containers are small so the times I have filled them up, some of the water did not make it into the bottle and spilt on the floor. A very small amount and the rational part of me says “dont worry about it” but the scrupulous part sometimes says that I did something sinful. I suppose as long as one is not intentionally spilling holy water out of disrespect, they should not worry about it. After all, when we are sprinkled with holy water by a Bishop or priest not all of it hits its intended target.