Agreed the amount of tris and EDTA is usually negligible for most downstream applications.
Though it's not too infrequent that I encounter applications where using >20% of volume DNA is necessary (for example, sequencing at our institution usually requires ~50% volume DNA for medium to low copy mini-prepped plasmids)
And since neither I nor anyone in any lab I've worked in has had stability issues when storing DNA in water at -20C, personal experience has not convinced me it is necessary.
I'm used to purifying troublesome proteins, and compared to those...DNA is a rock.
If a student in my lab can't keep plasmid DNA stable in water in the freezer, then major improvements in their lab technique are needed before attempting to work with challenging proteins. Students gotta learn to how to skate before they can play hockey.
Edited by labtastic, 28 December 2015 - 07:07 AM.