Bed wetting

My son is 2 years and 3 months old. Every night. He likes to have to have Drink before he goes to bed at around 8pm he's has his. Nappy changed before going to sleep every night. But he still wakes up in the morning with. A drenched bed. It's that soaked he sometimes wakes up during the night and refuses to go back to sleep. Is there a way we can stop this from happening his not toilet trained yet as in the progress of starting him as don't think his ready yet. I'm also. A first time m so never experienced this before and hoping someone can help on some advice he does have a protective sheet on there to stop it going on to his actual mattress. Any help would be much appreciated. Thank you