Drying Water Bladder

[tony]

Switch that thing out to one with an open top.
New hydrapaks you can turn inside out.
I do have a few like the OPs and have used the above tricks to dry it out.
Takes a few days sometimes

 

[hikenhunt]

I'm with tony, invest in one with a larger opening!

 

[Robertsericj]

I use paper towels and an old hanger to dry it out. Hang it upside down.