September 19, 2013
Water Filter Test: Is a Pump or Gravity the Better Water-Filtration Method?
By David Draper
Before my recent backcountry archery elk hunt, I decided it was time to upgrade my old PUR Hiker water filter. During my research, I realized filter technology has come a long way in the past decade and was torn between two different systems: the MSR MiniWorks EX pump style filter or a Platypus GravityWorks filter that uses, well, gravity to transfer water through the filter. In the name of research and my ongoing fear of commitment, I decided to try both. The MSR would stay in camp to filter water there, and the lighter Platypus system would be carried in my hunting pack to purify drinking water while on the trail of trophy elk.
MSR MiniWorks EX Microfilter
Alesha Williams, of Flying J Outfitters, had packed four collapsible water bags up to our camp at the head of the well-named Dry Fork, which gave us about 20 gallons of water to drink and cook with in camp—all of which needed filtered before use. The pump-style MSR MiniWorks initially made quick work of filtering the water (which came from a clear-running stream), though I don’t think it ever reached the manufacturer’s claim of 1 liter per minute. After about the first five gallons, it became difficult to pump, indicating a dirty filter. Luckily, the unit is easy to clean. Just unscrew the body from the pump, pop out the ceramic filter, and give it a quick scrub with the included green pad. The filtered water came out pure and clean-tasting with no chemical or charcoal taste.
Pros: Compact and lightweight, with a manufacturer listed overall weight of just one pound. Filter is easy to clean, and the whole unit is field-strippable for maintenance. Quick to deploy, the MSR MiniWorks requires no assembly in the field. Just screw the pump onto a water bottle or bladder and start pumping.
Cons: The pump is made to fit Nalgene and other similarly threaded bottles and hydration bladders. Trying to filter water into a pot, open-top bladder or other non-threaded containers is a pain, especially when a dirty filter requires extra pumping pressure. Users could fit the output nipple with a length of tubing to make this easier.
Platypus GravityWorks 2L Water Filter Kit
Coming in at just 11 ½ ounces, the GravityWorks is extremely lightweight. Weight-conscious hunters could even leave out the included soft-sided clean-water reservoir and a few accessories to reduce the overall weight even further. The system consists of primary reservoir for dirty water, a ceramic filter, and a length of tubing with included fittings for both Nalgene-style bottles, conventional water bottles, and even bottles and bladders fitted with push-pull caps. Though I never tried, Platypus also says you can fill bladders through their sip-tubes, which eliminates the hassle of removing the bladder from your hunting pack. The GravityWorks filter couldn’t be simpler to use: Just fill the dirty reservoir with unfiltered water, plug in the filter via the quick-connect valve, screw a bottle onto the cap adapter, and open the pinch clip to start the flow of water. When clean, the filter will fill a quart bottle in about a minute. The first quart through the filter had a slight chemical taste, but subsequent water tasted clean.
Pros: Fast and easy, though it does require a slight bit of assembly in the field each time. The filter, good for up to 1,500 liters, is easy to maintain by reversing the flow of water from the clean bottle to the dirty reservoir. After the first few times using the filter, I started cleaning the filter with each use to keep the flow rate up. It’s incredibly lightweight.
Cons: Prior to the trip, my biggest concern was filling the dirty reservoir in skinny water, such as the small trickle that was the closest water to camp. While not impossible, this task was challenging and it took some finessing to get two liters of water into the bladder each time.