You can't control how MUCH they drink, but you can control whether or not they drink by the pool.
Ask any campus officer about student behavior when they are drinking. They can't handle it!
Fights! Fights! Fights!
Diving into the pool and breaking their neck on the concrete floor (call any rehab hospital and ask about paraplegics who dove in the pool and broke their necks where alcohol was involved. My husband was one of those 23 years ago).
Does it ruin their fun? What about the fun of the non-drinkers who have to watch drunk people pull down their pants, pull down their friends pants, push people into the pool because it's funny, etc.
No way I would allow anyone drinking in the people or near the pool. No alcohol outside anywhere on my property.