Son question

So I’m a first time mom and I have a 20 month old son. The last 6 months or so I’ve started to realize he’s been waking up in the mornings head to toe soaking wet in pee. (He’s always been a heavy wetter but now its to the extreme) I mean his sheets, blanket, jammies, and diaper.. I thought he was possibly drinking too much so I cut down on his fluid intake, changed diaper brands, went up sizes but nothing has stopped it. Also, He drinks only water throughout the day and one sippy of milk at bedtime. So my question is has anyone else experienced this with their sons?