Untreated Kitty Litter in potting mix?

[up side down]

I've done a few searches, but can't find any reference to using untreated Kitty Litter in potting mix to help drainage and moisture retention, has anyone used it, not the clumping type just the very cheap kitty litter

Oh, since i'm in New Zealand, its no use give brands, or maybe it would, I could find out what they are made of.