I am not sure this article has a place on a hiking website but as I use one of these I thought I will put it on there anyway. You don’t really think about Hydration bladders being part of a persons equipment for hiking or trekking but I have used them a number of times in the past for training. 
And yes I wrote training because lets face it when you are home for long periods of time everyone tends to get lazy with all of the modern home comforts on hand. So I have a habit much to my wife’s dismay (I do a lot of walking in my day job as well) of heading out every now and then for a 15+ mile fast hike just to keep in trim. My average is to stay at over 4 miles an hour for as many as I can (usually 15-18 miles) which to me is enough for any normal day hike.
And because of the pace& time period I try to take as little as possible, some snack bars to keep me going and a water bottle which is usually empty after a couple of hours. Then a friend of mine who is a long distance runner suggested a hydration bladder under the jacket which after borrowing one from him I found out they are a great invention. Personally I wouldn’t take them out on long distance hikes because I would take my Mountop water filter bottle but on training hikes they are great. One day I am planning to hike over the Marathon distance of 26 miles just for something to do & I can safely say the Hydration bladders will be coming with me. So to everyone out there I would say try a Hydration bladders and other equipment that is available and if it works then why not use it. If after trying you find you don’t get along with it then put it aside like the old trekking boots that you just don’t want to throw away and let it gather dust.
My final thought has to be even though its not officially hiking or trekking equipment I am a firm believer in using & adapting what is on offer to suit my purposes.
