Yes, 22oz is a lot. A normal size jelly jar is 18 oz. find a food jar or can in your house that is close to 22 oz. for visual. However for a reservoir for like a humidifier or something like that, then I don't think is a lot. Not familiar with the zoo med reservoir.
Okay, just looked it up. The water bottle is good size. However the actual dish is way too small for a tort.
If you are going to use it as the only water dish then no. You need one big enough for the tort to get in and soak himself should he want. If you want to ad the reservoir for an added drinking water dish, then it would be okay.
Here is another option. I get these at Walmart pet section. They have a larger water dish and a removeable food dish. They use a 2 litre pop bottle as the reservoir (the ring below cap of bottle does need to be trimmed). As Wellington pointed you will need a soaking dish as well.