Finding someone who makes canteens out of actual tin is hard.
Most people end up with stainless steel canteens or enamel-bottles or modern day canteens they cover with cloth or leather. Which is obviously wrong. All of it. For the french, glass bottles are also hilariously overrepresented. And you also get a whole bunch of guys with those huge 2 liter steel canteens. No. Just no. They should hold a liter, possibly even less. They did not have those huge canteens.
If you cover your canteen with beeswax from inside and only drink out of the bottle every few weeks you are not going to die from it. If you are worried about this stuff, you should see our cooking gear. For example, we are using original WW1 french cooking gear. It is made out of lead and covered with tin, but half of the tin melted away. We were stupid once and deep fried in it, the fat caught fire and small parts of the tin cover melted away... But we ate from it anyway. Lel.
Also, you see the canteen behind mine? That is actually also mine. I bought 3 of these from a tinsmith. He made them out ot proper tin, so they are actually drinkable. But I am not using mine at the moment. The lead one is nicer, because its rusty from outside and it has a slightly nicer shape.
The thing I hate about my canteens is that I decided to use cork stoppers for all of them. Wooden stoppers are accurate, but they are a fucking pain to get in and out. Once you have them in the canteen, they just get stuck and if you want to just quickly take a sip (and take off the stopper with one hand) when not standing at attention, you are doomed, you can not do it.