Hi, K. -
My son who is 10 went through this and my daughter who is 5 is currently getting over this. It can be frustrating, but it is worth the hard work if you can work on it with him.
I suggest a company called Pacific International.
http://www.stopwetting.com/
After all of my research, I learned that wetting the bed is due to deep sleeping, not how much they drink before they go to bed. Both of my kids sleep very deeply. When you are 'waking' your son up, it is possible that he is still asleep!
My dad had a problem wetting the bed as a child and so did my brother.
Basically, this company works with you through an alarm that your son sleeps on. When the alarm senses moisture, it goes off, you wake him up, make sure he's awake, and help him go to the bathroom. You log his wetting schedule on a chart, send it into your counselor and he/she works with you on what to do.
It was wonderful for us! My son was dry within about 6 weeks with only a few sporadic wet nights after that, and my daughter has been dry for a few weeks now.
Hope this helps!
There's also another website which sells these alarms http://www.stopwetting.com/), but I definitely recommend going through Pacific International. Their success rate is amazing! We had a really good experience with them, and they work with you for however long it takes. It's nice to talk to someone who knows about the problem.
Unfortunately, a lot of doctors just prescribe medication, but this only treats the symptom and not the real problem, deep sleep. Using the alarm system trains the children to wake up when their bladder is full. Eventually, they learn to hold it and even go back to sleep, waiting until morning.