Get as hydrated as possible before leaving camp. Even if you end up peeing extra along the hike. Being hydrated from the start means having to carry less water in your pack.
I still don't trust that they have made soft, collapsible bladders to be toxin free. Any plastic will be leaching toxins. I certainly don't like the plastic taste. I use a 3 stage filter, including carbon, at the end of the tube from my internal water bladder. Carbon filters out a good percentage of the plastic toxins. As an added bonus, this setup doubles as a gravity filter.
Some trips require that I carry as much water as I can. So I would also need a bottle in each side pocket of my backpack. In my dreams, there are lightweight soft bladder-bottles made of titanium or stainless. I don't think they exist. Do I make due with plastic bottle bladders?
With most people taking soft bladder-bottles, having a separate cooking pot makes sense. If metal collapsible water bladders are not available, and you must have a stainless or titanium water bottle, does it make sense to have both a bottle and a metal cooking pot? Enter the bottle pot, such as the Vargo Titanium Bottle Pot HD.
If I am going to be boiling water or otherwise cooking in a pot, I bring along my Stanley Adventure stainless steel water bottle (no longer made). Other times I prefer to skip with cooking altogether, and bring only soft bottles to save weight. If I am hunting, I can cook with sticks.
I've been curious about using an insulated stainless water bottle as a cooking pot with built-in heat exchanger. The heat exchanger would be the air gap between the exterior and the internal reservoir, by cutting out the bottom and drilling some vent holes at the top of the exterior. The only insulated bottle I've found with a wide mouth for use as a 1 liter pot, is the Purist Founder, which weighs 14.4 oz. I was hoping for a cheap one to experiment on. Cheap bottles usually have the added benefit of being lightweight.
nsharry61 on WhiteBlaze enlightened me to the existence of soft bladders that are coated with metal or glass on the inside:
“As I understand it, Mylar is metal coated plastic with the plastic being there to provide structure to the micro-thin metal layer. In the case of the wine box liners, I would think the metal layer is likely on the inside to prevent any plastic taste from leaching into the wine.
On a completely alternative note, Specialized Bicycles manufactures a series of water bottles that are called Purist(TM). These are a flexible LDPE plastic bottle with a micro-thin layer of glass deposited onto the inside to prevent the plastic taste from getting to the water. It also reduces staining and bacterial build-up on the inside of the bottle.
So, as long as the lining is thin enough (a couple molecules thick?) and you don't mind using plastic as the primary structural material, it seems you can potentially get both collapsible glass and collapsible metal containers.”