Turner, 73, and Bach, 57, have been dating since 1986. They met at an industry party in London when Bach was working as producer for EMI. Reportedly, they've been engaged since last April, around the time when Turner received her Swiss citizenship. They have shared their lake home, Chateau Algonquin, since 1995.
Another source revealed to the NY Post that a reception may be held at their villa on the French Riviera.
This is Turner's second marriage. Her first, to Ike Turner, was a brief and turbulent marriage chronicled in the 1993 film What's Love Got to Do With It.