Designer [...]

[Dave Wilton]

> I know that we've been using the term "designer water" for quite some
> time - ever since bottled water became so popular.  It hasn't been as
> long ago as 1979, though.

The OED2 has "designer ____" referring to clothes from 1966. The first
citation is "designer scarves." "Designer water" appears in
rec.music.classical on 5 Aug 1989.

It seems to me that "designer drug" or "designer gene" is a different sense.
It doesn't denote something created by a prestigious artist or marketed
under a particular label, but rather something that is custom made. The OED2
has "designer drug" from 1983. "Designer gene" appears in sci.med.aids on 24
Feb 1990.