How do you remove hard water stains/spots.

Hand wash with vinegar. Dry immediately. Mine have never been in a dishwasher.

Here is their site, see if that helps.

http://www.tervis.com/use-care

I agree, vinegar will help. I, until we moved into this house, hadn't had a dishwasher since the nineties and my glasses are clear as can be. A lot of times this happens in the dishwasher. They should come clean, if they are stubborn, let them sit with vinegar in them for a while. If they don't come clean, they may be permanently etched.

If you need/want to run them in the dishwasher, try adding citric acid in your wash, I just fill my rinse aid compartment with it. My dishes come out shiny now, no more hard water stains.

the tumblers are plastic?...for the shower make a mixture of white vinegar and water 50/50 a dab of blue dawn dish soap and a dab of jet dry

I put a 1/4 cup white vinegar in the D/W

Make sure your D?W has a full Jet Dry cartridge (on the door).