Have You Tasted the Water in Your Child's Sippy Cup?

There have been times when Alex refuses to drink from his sippy cup even though I know he's probably thirsty. I don't always think to check the taste of the water in it, but when I do, it usually does taste funny, which explains his refusal. It occurred to me that maybe the soap on the valves wasn't completely washing off in the dishwasher, so I started rinsing the stuff in the baskets after the dishwasher stopped running. It seemed to help, but we still had the same problem once in a while. Finally, I switched to the First Years cups pictured, which have a built-in valve that avoids the soapy-taste problem. Caveat: I've noticed that they sometimes leak, so I'm careful to tighten the lid and keep them vertical when they're in my diaper bag.