Tom,

Sounds like you may have one of the "Real GI" canteens opposed to a real USGI canteen. If you look into the throat of the opening and it is flat instead of rounded or gently chamfered, that may be the case. If so, a true USGI canteen and lid shouldn't leak.

If that isn't the problem, I suggest Camelback bottles. I appreciate the bite valve set up and the loop for carabiner attachment. We have about 10 and they all work like champs. I just clip them anywhere I want and go. I carry them in my truck (read office), and just refill throughout the day. Another nice feature is they can be "rebuilt". Replacement parts for the bite valve, etc are available at most stores that carry the bottles.

Here is the website.

Good Luck