I suppose it would kill Wiggy's, or any other company, to make a single-wall WIDE-MOUTH BOTTLE...
Is the problem that they don't match the standard Nalgene size thread that many water filters use?
Have one of
these — made by Guyot Designs — on my Christmas list:
"63mm mouth works with wide mouth water purifiers & accessories." The tethered reinforced nylon lid is removable. Two other "models" carried by
EverestGear.com .