J.T.
I take white vinegar, as others suggested, and add it to the softener dispenser so it adds it to the final rinse cycle. To the vinegar, I usually add a few drops of some essential oil. Lavender is nice, rose is VERY fragrant. I usually just put some in the bottle of vinegar when I get it and then give it a few good shakes before I use it. I don't use any laundry softener this way, and rarely would have 'needed' it. Clothes are no more static-y in the middle of winter than if I had used softener and they or no more 'stiff'. It seems to work well for us.