So just what is a Lifesaver bottle? It's a filtration system which is apparently so advanced it can filter out microbes, viruses, and all forms of contaminants from even the dirtiest of dirty water that you'd otherwise never drink even to save your life. And it does so within seconds, not hours or even days. There's no foul chemical treatments to use, no boiling necessary. One bottle will last you through 1500 gallons of clean, safe drinking water. When the filter needs replacing, the device stops functioning. Protecting you from drinking water which would otherwise be unsafe.
The usefulness of this doesn't end with one person stranded alone after a crash. Shipments of these things can be airlifted into disaster zones and the victims can use them to filter their local water sources that might have been contaminated. Such a device would have been handy for Katrina victims right here in the US. Enough of these things flown in one time could save thousands of lives in areas such as Myanmar where severe flooding after storms destroyed all of the local drinking supplies. One plane load of these is literally worth dozens of airlifts of normal bottled water, thus also costing far less to ship. Since the filters last so long, you don't need to have a massive ground effort launched and humanitarian aid becomes that much easier to manage.
The military would see great use of these as well. Supply a solider with one of these bottles and he can drink from anywhere near the battlefield without having to lug several pounds of water bottles along with him, leaving more room for vital equipment he could otherwise not carry. It also comes with handy pressurized jets which can let field medics clean wounds more effectively on the front lines.
Even survival enthusiasts who stay out in the woods for days or weeks at a time would find the bottles useful. Again, mainly because they don't need to bring a huge load of water with them or risk drinking from an unknown source.
So every now and then, someone somewhere invents something like this that just makes you sit back and feel proud of what science and technology allow.
"It is pointless to resist, my son." -- Darth Vader
"Resistance is futile." -- The Borg
"Mother's coming for me in the dragon ships. I don't like these itchy clothes, but I have to wear them or it frightens the fish." -- Thurindil
Well. I guess that's that then.
And nobody is saying a solder can't carry his own canteen. Obviously if you know you're not going to be near a water source you'd be pretty screwed without some, right? But suppose your base has no water supply other than a dirty creek? Wouldn't you rather use this than fill your canteen with slimy creek water? And what's to stop the solider from filling this bottle as well and bringing it along too?