I have used/carried this Headtorch on every outdoors adventure I have been on in the last few years. Absolutely love it. 300 lumins, weighs in at 94g.
Source Hydration Bladder.
I don't know if you can still purchase the one I use. I use a 3 ltr in a neoprene cover. The cover gives me peace of mind that it is protected from punctures and won't leak in my bag. It also keeps the water cold which is nice on a hot day.