I use both. It's a technique I learned while preparing for backpacking at Philmont Scout Ranch in NM.

I have several platypus hydration bags and Nalgene bottles. When backpacking I have a 3 liter hydration bag that opens on top for filling (newer models have carrying handles that I recommend). Camelback has an extra wide mouth for ease of filling. I also carry two 2 liter platypus bags in case I need to carry extra water for dry campsites. Most of the time they are empty. Empty they take up little room and weight. I would consider replacing them with a 2 liter bag with carrying handle.

Then I have a standard Nalgene bottle that I reserve for crew cooking water. It stashes in a side mesh pocket. The nalgene is good for hooking directly to many filtering systems. It's also good for cooking as it has markings on the side for measuring amounts, useful for preparing dehydrated food.

In the other side pocket I have a large Gatorade bottle. It's cheap and disposable. I use this and only this bottle for smellable liquids, such as powdered Gatordae. It's easy then to make sure it goes up in the bear bag. I also wrap several turns of duct tape on this bottle. It's an easy holding device for the tape that's always in reach in an emergency and it also goes up in the bear bag as Philmont considers it a smeallable item.

For weekend trips and summer camp I have a 1 liter platypus that I stick in my day pack. Every scout at summer camp should bring a day pack with a water contained and small first aid kit. They'll also use it for their merit badge materials and swim gear if they need to change without returning to the campsite.

One of the complaints with hydration packs and Scouts is that it's difficult to monitor their intake to make sure they're not dehydrated. High adventure aged boys can be taught to make sure they stay hydrated. PLus everyone in the crew should be on rthe look out for signs of dehydration.

For younger scouts, especially at summer camp, we automatically assume they'll be dehydrated. Most boys are not used to being out all day in the summer in the woods. They don't stop to think about drinking water. So we constantly remind them, especially at lunch and dinner meals.

I would suggest a Nalgene for your son and perhaps a hydration system for you to start off with. Then as your son learns more and does more in Scouting, get him his own hydration system. It can be used as a subtle reward for his participation and growth as a Scout.

The more camp outs you go on, the more gear you tend to collect as the campout become more serious affairs and not just car camping outings where Scouts lug the bedroom pillows into their tents. Our ouys that are 14/15 and older tend to view using minimalist backpacking gear as a badge of maturity demonstrating their level of experience.

BTW, our troop issues new scouts a Nalgene bottle with the troop insignia on it prior to their first campout.