You can also render water relatively safe to drink using small amounts of bleach. I've done it a few times whilr camping. EPA.gov has instructions for it, you only need a few drops of bleach per gallon (roughly 3.75L) of water. One large bottle of bleach is enough to purify water for months at least.

https://www.epa.gov/ground-water-and-drinking-water/emergenc...

In Peace Corps we used a filter bucket and added bleach. Took very little bleach, though I don't recall how often we had to change the filter. It was essentially this: https://www.outbackwater.com/outback-5-gallon-gravity-powere...

It's probably a bit safer (easier to control) to use iodine which I carry for camping, even if only as backup. Once it's done it's thing, you can then put in some Vitamin C to neutralize most of the funny taste.

I don't think Iodine is safe to use for long periods.

Thru-hikers use it for six months at a time. It's safe enough for emergency use for someone with no preexisting thyroid issues.

But you don't know if you have pre-existing thyroid issues. Prolonged use should include monitoring thyroid function.

see https://www.cdc.gov/healthywater/drinking/travel/backcountry...

Water that has been disinfected with iodine is NOT recommended for pregnant women, people with thyroid problems, those with known hypersensitivity to iodine, or continuous use for more than a few weeks at a time.

Ok, so if clean water is unavailable for more than a few weeks, hop on down to the clinic and trade some ammo for a thyroid checkup? If you're planning for the end of the world, then yes you'll want a backup water plan. For realistic emergency scenarios iodine is a practical water treatment option.

Even easier to buy a few camping water filters and skip the boiling.

You’ve haven’t used those much then. Pumping water in the backcountry is a giant PITA. Even the clearest mountain stream ends up clogging the filters after a few liters and require you to back flush them. We despise using them and will often just boil unpurified water for our dinners.

Sawyer filters tend to be our favorite. Although if you only want to do a Nalgene amount of water and don’t mind some grit, then Steripens are a good option too.

My experience is quite different from yours with regards to clogging.

I used a Sawyer Squeeze daily for 4 months and probably only backflushed it 2 or 3 times. It definitely slowed down, but nowhere close to the amount of time it takes to boil water and wait for it to cool down.

The Katadyn Befree is my favorite right now because it's lighter with a considerably faster flow than the Squeeze. Some reviews from thru-hikers say it clogs faster than the Squeeze but I haven't had any issues so far. (Haven't thru-hiked with it yet though...)

Whole heartedly agree. A gravity system is highly recommended if people go the water filter route.

Second voice for the Gravity filter. Only way to go if you want liters of water at a time.

You don't even need that. You can filter through a piece of cloth and boil. It may not taste great but it's safe.