The campgrounds in Twin Lakes are dry so you'll need to fill in Leadville or Buena Vista. iOverlander.com has been really helpful for finding water-fill locations

We filled ours for free at Poncha Springs Welcome Center about an hour south of twin lakes. Also has a dump station for $10.

Leadville has a public fill and dump but the fill is $5 and dump is $10. We've heard that there is a free fill somewhere in town but don't have any details.