Water Purification: Particle Filters

The modern camper has a wealth of resources for staying healthy while anywhere in the world. Water is an essential part of camping, and if you do not want to lug heavy bottles of water around, you must invest in some type of  water filtration or sanitation system while camping. According to the Center for Disease Control, boiling is the best option. However, a combination of filtration and sanitization is the second best form of water purification.

When choosing water to use for drinking, the source is important. Look for running water, such as from a stream or river. Avoid water with algae or in stagnant ponds and lakes. Stay away from water found near roads or agricultural fields. This water can have harmful pesticides or chemicals and contaminants like tar.

The modern camper has many choices when it comes to water purification.

  • Boiling
  • Filtration
  • Sanitization


Done correctly, boiling kills off Protozoa and viruses and will always be the safest method of purifying your water. To properly boil water bring it to a rolling boil for one minute. Remember, at altitudes greater than 6,562 feet (greater than 2,000 meters), you should boil water for 3 minutes. I usually play it safe and boil for three minutes no mater where I’m located.

But, boiling isn’t always convenient. That’s why human kind has invented the portable water filter.

Camping with Filters

MSR MiniWorks EXFilters are mechanical purifiers, removing particles and contaminants from water by forcing the liquid through a porous material, physically blocking the contaminates. Filter material can be glass, ceramic and charcoal; many filter units use a combination.

Which type of filter you choose depends on the type of bug you want to remove. Bacteria can be filtered with a particle size of 0.4 microns or less. While a filter with a one micron rating will remove protozoa, like Cryptosporidium or Giardia, eggs, and larvae as well.  So rule of thumb, purchase a filter with the smallest micron rating you can afford. Check out the MiniWorks® EX from MSR®, it’s one of our favorites.

Viruses on the other had can’t be filtered and must be handled with a chemical disinfectant. More on those in our second post in this series.

Look for a model that weighs less than 20 ounces, is easy to use, and simple to clean. Units that offer a warning sign when the filter is at capacity can also help keep you safe while camping. A filter that is at full capacity can leech unwanted bacteria and contaminants into the water, risking your health. Depending on how many people are camping, the flow rate of the filter is also important. An average flow rate of one liter per minute is enough for a few campers, but if you have a larger group, you will want a greater flow-rate. Large gravity filters are ideal for larger groups.

Filtration pros: Effective at removing common water contaminants, lightweight,
inexpensive, and easy to use.

Filtration cons: Can be hard to locate new filters, may not eliminate all bacteria and
viruses, can clog and fail.

Look for part two in the water purification series soon!

What filter is currently in your pack?

MSR MiniWorks EX Microfilter

I’m doing some research on micro filters in preparation for some hiking / camping trips planed for 2013. If funds allow, the MSR® MiniWorks® EX is one I intended to pickup and field test — I’ll update this post with my experiences. In the mean time, here are some reviews that have convinced me this model is one to try. If you’ve used the MiniWorks EX, please share your thoughts in the comments section below.

Made in the USAThe founders of Cascade Designs® setup shop in 1972 to produce Therm-A-Rest® sleeping pads. By 1991 they had released the first MSR® water filter, the WaterWorks®. Today we’re looking at the WaterWorks grandkid, the MiniWorks® EX Microfilter.


Weight 1 lb / 456 g
Width 2.75 in / 7 cm
Length 7.5 in / 19 cm
Filter media Ceramic Plus Carbon
Filter pore size 0.2 microns
Flow (L/min) 1 liters per min
Flow (strokes per liter) 85
Cartridge life ~2000 liters
Cartridge replacement indicator Yes

More Info


Worth every penny!

November 8, 2009 By R. Zamudio from Amazon.com

[editor’s note: Corrected some spelling errors. Possibly the best review I’ve ever seen on Amazon and a major factor in my decision to try this filter.]

I researched filtration systems for almost a month before settling on the MSR miniworks. I figured I could just go pick one up at the local Cabela’s or REI, but BOTH retail stores were sold out of these, while there was still a good supply of the other MSR and Katadyn filter systems on the shelf. I took this as a sign that this is the filter to have and ordered it from Amazon, and it has been worth every penny. Read on….


MSR MiniWorks EX


In Camp:
The filter is very simple to use and has a good output-per-pump ratio. You never really feel like you are doing more work than you should for the amount of water you are pushing through, especially if you take into account the fact that every pump is worth about one gulp of nasty water that you WON’T have to drink. If you do see a diminished output, simply unscrew the filter housing and give the element a light scrubbing. We were taking water from a brown lake that is loaded with tannins and we would get about 2 liters through (about 2 full-size nalgene bottles worth) before we noticed the filter could use a cleaning. Tannin-loaded water is supposedly some of the worst for clogging these ceramic filters, so if you have cleaner water sources at your site than we do, your element-cleaning cycles should be farther apart. The water came out crystal-clear and almost tasteless. It didn’t taste like Dasani bottled water, but it definitely didn’t taste like tea-colored lake water either. Pretty much neutral. More importantly, it tasted CLEAN and nobody got sick. Also, the MSR Miniworks requires no chemical additives but still claims to filter everything but viruses. The chance of contracting a waterborne virus from a U.S. lake or stream (think Polio, Hep-A, SARS, and a few others which you have probably had vaccinations for) is far lower than getting sick from bacteria or parasites. If this still bothers you, you can still boil your clear, clean-tasting water just to be sure.

Out of Camp:
The maintenance on this filter is very simple. The unit breaks down into 4 major parts, and the wrist pins on the pump assembly are quick-release squeeze-and-push types. You can literally have this thing stripped down and cleaned completely in about 5 minutes, and that includes the sterilization of the filter element. A couple dabs of silicone grease or chap stick is all you need to lube it up when you are reassembling the unit.

The Hidden Bonus:
$80 may seem like a lot for a water filter, but the MSR miniworks pays you back exponentially…
Prior to buying a filtration system, everyone in our backpacking party hauled their own water needed for the entire trip. We would calculate what we needed for hydration and cooking each day, plus a bit more just in case, and we strictly stuck to these rations. We would have enough water, but never enough to truly quench one’s thirst. Having this filter in our party allowed us to drop about 15 lbs carried, per person! Plus, we didn’t have to pack out a bunch of empty water bottles anymore. One filter supports 4 of us and we now drink as much as we want. When you think about how important hydration is to your body’s systems (Read Cody Lundin’s “98.6 Degrees” book and you will know more about the subject than you ever wanted to), shelling out $80 to have clean, safe water on-demand anywhere you can find a water source is a small price to pay.

-Put a coffee filter over the hose inlet and secure it with a twist-tie, rubber band, or fishing line. This will make your MSR filter pump more efficiently for longer without as-frequent element cleaning. Every time you clean the element, you are scrubbing away some of the element’s overall diameter. When it gets too thin, you have to get a new element. Fewer cleaning cycles = prolonged filter life and more money remains in your pocket. Filter element, $40. Coffee filter, 3 to 4 cents.

-Bring a spare filter element if you are going on an extended trip or are going to be absolutely dependent on this filter for your drinking water while you are out! Meaning: hiking back to your vehicle and driving like a madman to the nearest 7-11 for a drink before you go into a coma from dehydration is not going to be an option! The word is, these ceramic elements are fragile. Finding this out at the wrong time and being caught without a spare would be a very bad thing. If you spent the cash for the filter and other people in your party use it, have them pony up the $40 and buy the spare element for you. It’s only fair…. right?

-USE A NALGENE BOTTLE WITH THIS UNIT (or other similar one that will attach to the adapter). The motion created while you are pumping is far too violent for precision-aiming the output stream into any loose container, except for a bucket. You can also attach another length of rubber hose to the outlet and run that to your container, but we have not tried this yet. The Nalgene bottle seemed like the simple solution to use with the filter and we filled our other containers from this bottle.

{Product use update} – Our party of 3 did a 4-day back country hike in the Grand Canyon (search: Tanner Trail) this past winter. This is definitely NOT a tourist trail, and the first 2000-3000 ft of elevation is not much a trail at all. The noted only water source along this entire route is at the very bottom of the canyon, the Colorado River. We were able to augment our hike-in water supply by searching for pools of water trapped in depressions of the rocks near the places where we made camp, and pumping water from them using the MSR Miniworks. I don’t even want to think of what was in those water pools, but what came through the filter was clean and refreshing. We made notes of the larger water pools, which allowed us to lighten our water load on the hike-out and stop by the pools for a top-off when we needed it.