Backpacker Magazine – December 1998

Water Filter First-Aid

Make sure your water purifier doesn't leave you high and dry.

by: Kristin Hostetter

My tongue feels like a wool sock, my lips are like snakeskin, and I'd cry if there was enough moisture left in me to produce tears. There isn't, so instead I plod along, hoping there's water up ahead. Half an hour later I'm still walking.

Finally, I'm on my knees next to a cool ribbon of liquid salvation, frantically pumping my filter. But the #!*&#!! thing is clogged, so I dunk my face and slurp like a Texas racehorse in July.

I was lucky. The water was apparently cootie-free and I didn't get sick afterwards. But the lesson learned is that it's better to prevent filter breakdown than to take chances with your health. The information below will help you identify and head off common malfunctions. (Note: Some techniques may not apply to your filter, so before tinkering, read the manufacturer's instructions. If you're unsure, call the company.) To extend your filter's life you should also:

• Handle with care. Dropping a filter can cause cracks that let nasties through the cartridge.
• Avoid the big freeze. In cold weather, be sure your filter is thoroughly thawed before pumping. Wrap it in a T-shirt and put it in the bottom of your sleeping bag at night.
• Make a pre-prefilter. In thickly sedimented water, wrap the prefilter with a disposable coffee filter, T-shirt, or bandanna, and secure with a rubber band. Rinse as needed.
• Bleach it clean. Pump a solution of 1 capful of household bleach and 1 quart of tap water through the filter.
• Let it breathe. So moisture can evaporate, store your filter in a mesh bag-not a zipper-lock or nonbreathable sack.
• Don't overwork it. There's no need to filter water you'll boil for oatmeal or spaghetti.

Problem Leaking from the pump housing

Cause: Imperfect seals allowing water to escape as you pump.

Solution: Take the filter apart and check the O-rings. If they're torn or worn, replace them with new ones from the manufacturer or your local outdoors store. If they're just dry, see "Prevention."

Prevention: Lubricate all of the O-rings with silicone.

Problem
Filter pumps, but won't draw water

Cause: Filter needs "priming." To suck water through the hose and filter, you need to create a vacuum effect. All seals and valve systems must be tight.

Solution: Filters "prime" in different ways. For example, with the PUR Hiker, remove the filter element and swish it around in water. With the MSR Miniworks, clean the valve surfaces per manufacturer instructions to remove grit that can break the seal.

Prevention: Keep the valves and seals clean and grit-free, especially before you store it.

Problem
Splintered or torn hose ends

Cause: Forcefully attaching and detaching prefilters, bottle adapters, or other accessories.

Solution: With a sharp blade or scissors, snip an inch off the damaged hose end.

Prevention: Wet the hose end when reattaching it, and slide it gently over the nozzle.

Problem
Difficult to pump

Cause: Large chunks of sediment sticking in the prefilter element.

Solution: Clean according to manufacturer's instructions, either by wringing the sponge (PUR Hiker) or backflushing (Sweetwater Guardian).

Prevention: Pump the cleanest, clearest water you can find. Let water sit in a pot before pumping so sediment can settle to the bottom.

Problem
Cleaned prefilter but it's still difficult to pump

Cause: Smaller chunks passed through the prefilter and clogged the main filter element.

Solution: Clean according to instructions, either by scrubbing (MSR Miniworks, Katadyn Pocket Filter, or Sweetwater Guardian) backflushing (General Ecology First Need), or swishing the filter element in clean water (PUR Hiker). Also, rinse plastic filter housing in clean water before reassembling.

Prevention: Let water settle before pumping and pump from still pools rather than roiling whitewater.

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