Water treatment: Always. Since heating water to boiling suffices to treat it, I don't bother treating water that I use to cook, or to make coffee or tea. There are also a couple of sources that I trust, like the artesian spring on the east side of Slide Mountain in the Catskills. The sources I trust are very few.

Food storage: I use bear boxes, cables, and poles where they're provided. I use a canister where the law says I have to. I'll sleep with food during the part of the year when the bears are asleep, or if I'm more than 4-5 miles away from a settlement in an area where hunting is permitted. (That combination means that a bear that I encounter is likely not to see humans as a food source and likely to have a healthy fear of humans.) The rest of the time, which is most of the time, I hang. If I don't spot a suitable tree, I'll hang between two unsuitable ones. I can always find a pair of trees where I can get the rope over branches, even if the bag would hang too close to the trunk.

I don't hike in the West, so grizzly are not a concern. I'd imagine that the whole changing-clothes ritual is a bit overblown. I'm a human, I'm going to smell like human food. I don't think I have any good way on trail to get the scent out of hair and beard, for instance.

I haven't had a bear bother my food yet. I've had a raccoon try to drag my (foodless) pack away, and I've had a porcupine steal my skivvies out of my tent vestibule, but my food's always been safe so far.