We only had an entry for plain water.

dat/data.base

@@ -1678,6 +1678,29 @@ hobgoblin
 	The ninety-nine years is nearly up, so trouble may soon be
 	heard of on the road between Hurworth and Neasham.
 		[ A Dictionary of Fairies, by Katharine Briggs ]
+holy water
+	"We want a word with you," said Ligur (in a tone of voice
+	intended to imply that "word" was synonymous with "horrifically
+	painful eternity"), and the squat demon pushed open the office
+	door.
+	The bucket teetered, then fell neatly on Ligur's head.
+	Drop a lump of sodium in water.  Watch it flame and burn and
+	spin around crazily, flaring and sputtering.  This was like
+	that, just nastier.
+	The demon peeled and flared and flickered.  Oily brown smoke
+	oozed from it, and it screamed and it screamed and it screamed.
+	Then it crumpled, folded in on itself, and what was left lay
+	glistening on the burnt and blackened circle of carpet, looking
+	like a handful of mashed slugs.
+	"Hi," said Crowley to Hastur, who had been walking behind Ligur,
+	and had unfortunately not been so much as splashed.
+	There are some things that are unthinkable; there are some
+	depths that not even demons would believe other demons would
+	stoop to.
+	". . . Holy water.  You bastard," said Hastur.  "You complete
+	_bastard_.  He hadn't never done nothing to _you_."
+	"Yet," corrected Crowley.
+		[ Good Omens, by Neil Gaiman and Terry Pratchett ]
 hom*nculus
 	A homunculus is a creature summoned by a mage to perform some
 	particular task.  They are particularly good at spying.  They