I’ve never liked the idea of a water bladder inside my pack. Sure, it’s convenient to be able to drink from a tube while hiking, but it takes up such valuable room inside the pack (especially since transitioning to a 34 liter pack for most of my multi-night trips). It also feels dangerous. If that bladder springs a leak for any reason, my gear gets soaked. If it’s a cold weather trip and I’m relying on down insulation, that’s bad news. So I’ve always just kept water bottles in the side pockets of my pack and pulled them out when thirsty. But that drinking straw was so nice…

One day I came up with what I think is a pretty cool solution (as I’m sure others have as well). Why not just stick a tube down into the bottle and drink from a reservoir on the outside of the pack? Seems simple enough. And it turns out it is simple!

There were only a few things to figure out. First, how to get the tube into the bottle? I got and extra lid for my Nalgene bottle and some quick disconnects used on drinking tubes to play with. I drilled a hole in the lid large enough for the barbed stem of the disconnect, hot glued the disconnect in place, then attached a short section of hose inside the lid to reach the bottom of the bottle. Then I could put the other half of the disconnect on the drinking tube and away we go!

I quickly found out that I needed a way to let air into the rigid Nalgene bottle so I wasn’t sucking against the vacuum force developed when removing water. So I drilled another small hole in the lid. It worked, but now I had a problem when bending over that I’d get a tinkle of water on my shoulder coming out of that small hole. Annoying, but manageable for now.

I made a couple of minor tweaks and transitioned to using an empty pop bottle because it was way cheaper to prototype with than buying new Nalgene lids. I continued with the air holes, but then somewhere along the line I realized that the flexible pop bottles didn’t hold a vacuum at all–they would just collapse if needed, very similar to a water bladder. Viola! Just don’t use a rigid bottle and you don’t need an air vent. Sure, the bottle collapses a bit when drinking, but as soon as you remove your mouth from the tube air rushes back in. And you can even give it a little blow to fully expand the bottle if needed.

After making a new lid with no air hole I had a working system that I was happy with. But a few more improvements came along.

1. The bite valve I had been using from my old water bladder is really overkill, especially when trying to cut additional weight. I decided to remove the valve and use a simple hose clamp instead (it works great).
2. If you select just the right hose, you don’t need to make modifications to a lid. The SmartWater flip top lids happen to have an inside diameter that fits snugly with a 3/8″ OD silicone tube to create a water tight seal. So all that’s needed is to pull the tube through the blue opening in the lid. Kudos to SmartWater, the lid is compatible with any pop bottle you may want to use. And reusing a pop bottle makes it easy to replace if you forgot to clean it out after a trip and don’t want to battle the funk.

After playing around with several bottles, I landed on using empty 1.25 L coke bottles as my container of choice. The diameter is perfect for the side pockets on my pack, and the classic Coke shape with the reduced diameter near the base help hold it securely in the pocket. With a bottle on each side of my pack I can carry 2.5 liters for long hauls between refills. The Coke bottle is also the lightest of any of the bottles I tested, an added bonus!

This really is a great system. I’ve been using it for years now and don’t have anything negative to say about it at all. But the system had one more trick up it’s sleeve that I didn’t realize until last fall after a fellow backpacker pointed it out…

I use the Sawyer mini filter for all my filtering needs. This filter style requires and occasional back flush go clear out the filter element, and I had been carrying around the included Sawyer syringe for back flushing. But because the silicone hose makes a tight seal with the SmartWater lid, and because I got rid of the bite valve long ago, I can use my fresh water bottle with drinking tube as the back flush device. Just push the hose onto the clean end of the filter and squeeze the bottle. One less piece of gear to carry (and lose). Winning!

If you want to make your own setup, the hose and hose clamps that I use are available in the shop. I suggest going with 4′ of hose and cutting it to the length you like.

If you’re looking for a weight breakdown and how it compares to other reservoirs, see below.

DIY Coke Bottle Reservoir Weight Breakdown

Item	Weight
3 feet silicone hose	40 g
1.25 L Coke Bottle (no lid)	36 g
Shutoff clamp	6 g
SmartWater lid (flip cover removed)	5 g
Total	87 g

Water Reservoir Weight Comparison

Product	Dry Weight	Weight / Liter
DIY Coke Bottle - 1.25 L	87 g	70 g/L
DIY Coke Bottle with extra bottle - 2.5 L	126 g	50 g/L
Platypus Hoser - 2 L	102 g	51 g/L
Osprey Hydraulics LT - 2.5 L	167 g	67 g/L
HydraPak Shape-Shift - 2 L	139 g	69 g/L