Platypus bladder replacement caps

Have you tried calling and emailing Cascade Designs?  I’ve always had decent service from them, although I admit that their responsiveness does seem to have slipped a little in the last few years.

im also in the Seattle area so in a pinch I can drive up to their service bay in the S. Seattle industrial district.  Not that anyone should spend $10 on fuel and time to get ten cent caps. 😂

I use the 1l in sport cap and plain cap.  Found out the hard way that they’re not swappable (leak)

On my plain cap version, the lid from a 24oz plastic coke bottle fits (with less thread purchase area) and is leak proof.  I use one and carry one as a spare in case I lose one in the field

Iirc, the cap from the 70oz is the same as the 1l plain cap so the coke cap may work.   Cokes bottling is regional so not 100% they’re the same in your area but give it a shot.  Worst case is you mix a rum and coke

Smart water bottle caps or similar size have worked fine for me. I keep a spare in my pack in case I lose a cap from either my platypus or my water bottle.

I was in the middle of packing for a 7 day trip needing the Platy bottles so I just tried Smart water caps and they’re leak free on both the plain cap and sport cap version of the platy bladders.  They have more thread purchase than the coke caps so if you have a choice, go with the smart cap