This MSR Gravity filter changed backpacking for me. Pumping water for a family of five, day after day on the trail, sucks all the fun out of backpacking. This filter eliminated the pumping and returned my sanity. All you have to do with this filter is scoop up 10 liters of water in the dirty water bag, attach the hose, connect your water bottle, and sit back and relax.

The filter is good enough to keep you safe from all the usual protozoa and bacteria, and the flow rate is a solid 1.5 liters per minute when the filter is clean. The 1,500-liter capacity is on the low side, and replacement filters are around $50, but frankly, this expense is well worth the convenience. My only real gripe about the MSR Gravity filter is that the filter clogs with sediment rather quickly (in part because you’re sending 10 times the water through it each time you use it, relative to the rest of these filters) and requires regular back-flushing. It’s actually no worse than any of the rest of these, though. It just feels that way because it filters so much more water.

The MSR Trailshot is a lightweight hand pump with a hose that makes it easy to filter water from shallow streams where filling a bottle-style filter is difficult or impossible. It does take some hand strength to pump the Trailshot, and it would not be my top pick for an extended trip. After you pump about 2 liters, your hand is going to be tired. But if you’re in areas with frequent but not large water sources—alpine streams, for example—this works really well. I’ve used it on many a day hike where I knew there was a water source, carrying less water than usual and drinking direct from the stream. My main gripe about the Trailshot is that it’s expensive for what it is. The Sawyer and the BeFree are a better value.

If you’re hiking anywhere with extra-sketchy water—for example, areas where cattle share water resources or where you don’t know anything about what’s upstream—chemical purification is the way to go (in extreme cases, go with filtration and then purification). Aquamira is a chlorine dioxide treatment that kills everything, including viruses. The downside is that your water tastes a bit like a swimming pool. Part of the reason I like Aquamira is that it has the least taste of any of the chemical treatments I’ve tried. I relied on Aquamira extensively while trekking in India and Laos.

Aquamira is also quite reasonably priced. However, if you just want an emergency backup in case your filter breaks during a backpacking trip, Katadyn’s Micropur tablets ($13 for 20) are a better option, because they’re smaller and lighter than the Aquamira.

When just about anything could be lurking in the water, the MSR Guardian is the filter/purifier to get. It’s expensive and heavy and requires pumping, but the Guardian is the perfect filter for handling anything. The Guardian filters down to 0.02 microns, which will remove even viruses. It’s also designed to be self-cleaning, which makes field maintenance incredibly easy. It’s rated to pump 10,000 liters, which is good because replacement cartridges are very nearly as pricey as the whole pump ($240 at REI).

The Guardian is a pump filter, but if your arm is getting tired just thinking about the old days of pumping water, fear not. The flow rate is actually the best of any filter in this guide. It does take some effort compared with a gravity filter, but it’s not too bad. Because it screws right onto a Nalgene bottle, it’s pretty easy to crank out a couple of liters in hardly any time at all. You can use a hose to pump into any bottle if you don’t have a Nalgene, though this does make the process a little more awkward.

I think the Guardian is overkill in most of the US (I’m sure there are exceptions), but this is the filter I bring when traveling abroad. I haven’t tried it, but there is also a gravity-fed version of the Guardian ($310). It’s essentially the same as the MSR Gravity Filter above. It just runs the water through the Guardian filter/purifier.

I like Epic’s water filter because, from outward appearances, it just looks like a Nalgene bottle with a straw lid. This is handy in situations where you don’t want to offend anyone, but you definitely want to filter the water. I wish I’d had one of these when I lived in Mexico.

The Epic has two filters, one intended for domestic tap water, which I did not test, and one intended for outdoor use. For anything other than your home tap water, you want the outdoor filter. Using it is simple. The lid fits on any Nalgene water bottle, if you’ve already got one you can buy The Answer 2.0, which will fit any wide-mouth water bottle. The Epic claims to filter 75 gallons before you need to change the filter. Replacement filters are $20 when you buy two.

I did not buy the Grayl bottle because I wanted to survive in a postapocalyptic hellscape; I bought it because I wanted a discreet water bottle in the Philippines. However, the word “discreet” does not apply to Grayl’s operation. Put dirty water in the outer canister, place the internal canister on top, and press down to force the water manually through the filter. The GeoPress is basically an MSR Guardian without a lever. It’s fast—Grayl says it takes under eight seconds to filter 24 ounces of water—but I do need to put the bottle on a level surface and use all my body weight to press it down.

The GeoPress uses electroadsorption and an activated carbon filter; it filters out pathogens, particulates, heavy metals, and odors. I like it because it’s amazingly fast and simple to operate; it’s durable enough for emergencies when camping and backpacking; and it comes with its own vessel and drink spout. My kids are also extremely picky when it comes to drinking water, so I needed something that would filter out bad smells and tastes. It also eliminates one problem that comes with the Lifestraw, which is that you have to forcibly sip the water through the filter yourself. This sucks (literally). With the Grayl, it’s self-contained in its own vessel, and you can sip like a normal person. Replacement filters are also semi-reasonably priced at $30 a pop. —Adrienne So

The Lifestraw is alarming. No one wants to put their face near dirty water sources that you definitely shouldn’t drink from straight. When I tried it at the slough near my house, my daughter screamed, “No, Mommy, no!” The main problem with Lifestraws is that you have to use the force of your sucking to get the water through the filter, which I dislike. You also can’t use it to filter water for cooking, and your other family members will probably refuse to use it.

However, it’s extremely small, cheap, and light, and it works! It’s a decent backup option to have in your kit (I prefer a TrailShot or water treatment drops myself, but you do you). I’ve also tried the LifeStraw Sip, which looks a lot better when you put it in random water glasses, and I also use the Lifestraw Go when we visit family in the Gulf South, where my picky children would rather wither away into a husk than taste any hint of brackishness or sulfur in well water. They all work! But there’s better options. —Adrienne So