Drift Falls is located on the Rainbow Falls hike. Park there and hike past Rainbow and Turtleback to reach the falls. The hike is 4.0 miles round trip and the waterfall is around 80 feet long.
Stay on the trail heading past Turtleback Falls. The trail heads up the right side of Turtleback and continues upstream. In about 10 minutes the trail ends at a fence and no trespassing sign. Head left towards the river and as you make your way through the trees you will see the falls.
Apparently Drift Falls was once a very popular water slide for many visitors. It even earned the nickname "Bust Yer Butt Falls". Nowadays the land owner strictly forbids any trespassing as you can tell from the many signs posted.
You can get a great view of the falls from what feels like a small island in front of the waterfall. However, this really is your only shot available. The area is beautiful, but the waterfall is not very special or memorable. Being just upstream from Rainbow and Turtleback makes it worth a visit though.