Portable Water Purifier

Portable water purifier can help make murky river or lake water clean enough to drink. They can filter bacteria, protozoa (cysts) and viruses.


Look for models that mention what contaminants they can remove. Some can only remove bacteria and cysts; others can also get rid of viruses.

Some models have a separate device that holds the water, while others combine the container and UV lamp in one. Chemical treatments like the Katadyn Micropur tablets, Potable Aqua purification tablet and Aquamira water treatment drops are simple but require a little more patience.


SteriPEN kills bacteria, protozoa, and viruses with ultraviolet light. This deactivates the pathogens by wrecking their DNA, making it impossible for them to reproduce and cause infection. Unlike water filters, it doesn’t remove chemicals or minerals, but it’s still more effective than drinking untreated water.

It’s easy to use, with a simple button that turns on the bulb and a wand that you insert into a bottle. You press the activation button (once for one liter or twice for 0.5 liters) and stir the water until the LED lights under the button flash green, which indicates that it’s done. Occasionally, you might see the lights turn red as the device struggles to treat turbid water. If this happens, agitate the water more vigorously and try again.

A spectral analysis of the SteriPEN’s UV light yielded an intensity maximum at 254 nm, which matches the wavelength most effective in disinfecting water. Its important to note that droplets in the neck and cap of a bottle are not sterilized by the SteriPEN, so it’s recommended to dry them thoroughly with a towel before using again.

Compared to other devices, the SteriPEN is fast, killing bacteria and protozoa in about 90 seconds and destroying viruses in 48. That’s a big advantage in the backcountry, where waiting for water to filter can be a real test of your patience.


The Lifestraw is an award-winning product developed as a practical response to the billions of people worldwide who lack access to clean drinking water. It has the ability to take any water source (even a dirty puddle or muddy slush) and make it drinkable.

It works by sucking water through a filter that has hollow fibers filled with microbes and sediment. This catches any bacteria, protozoa, or parasites that might be in the water so it is safe to consume. It is reusable and runs on a simple mechanism that requires no batteries, chemicals, or moving parts. It is also portable, lightweight, and comes with a lanyard attached to the end so it’s easy to find when you need a drink on the go.

You can extend the lifespan of your Lifestraw by backflushing it after every use, which clears out any organisms that might clog the pores in the hollow fibers. It does not, however, remove viruses such as giardia and cryptosporidium. If you’re concerned about that, consider a GRAYL Geopress Water Purifier Bottle or an ultraviolet Steripen.

Other methods of water filtration require extra equipment like a pump or iodine tablets, take longer to complete, and can leave a chemical aftertaste in the water. The Lifestraw is a great addition to any bug-out bag, backpacking kit, or emergency survival tool because it’s instantly ready for use and doesn’t require any training to operate.

GRAYL UltraPress

The Grayl Ultrapress isn’t as tiny as a Steripen or as light as a Katadyn Guardian but it’s far more versatile and easier to use than either. It uses a push system where you fill the outer sleeve to the maximum fill line, insert the inner bottle into it and then press down. The inner bottle contains a filter cartridge that filters larger particulates like sediment and microplastics as well as chemicals, pesticides and heavy metals. It also filters viruses and bacteria using a mix of non-woven ceramic fibers and powdered activated carbon that’s claimed to bind them.

The patented design is a big step up from traditional filtered water bottles and the company says it’s capable of purifying three litres per minute. The process requires a little bit of oomph to press down, which is why it’s important to place the inner container low against your abdomen on a stable surface like a bench or rock.

While it’s primarily intended to be used for international travel where backcountry water sources often harbor viruses that standard filters can’t eliminate, outdoor adventurers and campers will find it useful in many other situations as well. It’s compact enough to fit in a pack pocket and the outer Ti cup can be used as a pot for heating water over a fire or hot coals.

MSR Guardian

Mary wants to go backpacking in Peru but is worried about waterborne illnesses that would derail her trip before she even sees Machu Picchu. She also doesn’t want to spend all night boiling her water in a pot on her tiny backpacking stove, and she’s tired of having to clean and refill her wide-mouth Nalgene bottle over and over again. So she picks up the MSR Guardian Gravity Purifier.

It comes with a fine-mesh pre-filter that prevents large particles from making their way into the main filtering system, which eliminates the need for backflushing. And the whole system can treat up to 10,000 liters before it needs to be replaced, which is more than enough for four people to get clean water on the trail.

As for the filtering, it uses MSR’s game-changing Advanced Hollow Fiber technology that’s essentially a bundle of spaghetti-like straws. These straws are dotted with microscopic holes that are big enough for water molecules but too small for bacteria, viruses, protozoa and dirt. The microbes and dirt are physically trapped, which is different from chemical or UV treatments that only kill the critters via chemical or radiation.

The MSR Guardian is super easy to use: just screw it onto the bottle or reservoir you want to fill, attach the hose and start pumping. It’s a bit slower than other hand-pump filters at a rate of 1 liter per 2 minutes, but it provides much better virus protection than most other systems and is very durable (it has withstood lab drop tests of 6 ft).