Geoscience Reference
In-Depth Information
Note:
Most filter manufacturers rate their filter life with an “up to” gallon rating based on
use with very clean water. Unless you know that you will only use your backcountry water fil-
ter with extremely clean water, figure on a realistic life of roughly one-third the manufacturer's
rated life. Sad, but field tests show that this is generally true.
Occasional or Emergency Use
For simplicity, one of the certified purifiers (Katadyn, First Need, MSR, etc.) would be a good
choice. If viral contamination is a major concern, I would not rely solely on the iodine resin in
most purifying filters, but would either pretreat the water with a chemical treatment, then run it
through the purifier to remove protozoa cysts and the bad taste of chemical treatment, or post-
treat filtered water with a SteriPEN. Of course, if you are going to do this, you might as well
buy a cheaper, longer-lasting filter and treat the water with chemicals or a UV SteriPEN when
filtering suspicious water. My personal recommendation is to buy either an MSR or Katadyn
filter with a carbon core, and also a SteriPen. I suggest purchasing a compact Polar Pure iodine
crystal kit (it treats up to 2,000 liters of water) as a backup in case your SteriPEN fails. Use the
UV SteriPEN to zap clear, sweet-smelling water without bothering to filter it first. If using
scummy water, such as city duck ponds or brackish water in the backcountry, first run the
scummy water through the filter to clarify the water and remove bad tastes, toxic chemicals,
and most (if not all) microorganisms, then zap it with your SteriPEN to make extra sure any
stray viruses are killed. Also stock at least one spare filter cartridge, since the cartridges can
clog quickly with dirty water. I find that when using filters with ceramic cartridges to treat rel-
atively clear water, the carbon cores in the ceramic-type cartridges tend to stop removing chlor-
ine and other bad tastes long before repeated cartridge cleanings have worn down the ceramic
filters to the point where their bacterial filtering capabilities are reduced and they need to be re-
placed. These types of water filters come with a gauge to tell you when cartridge cleanings
have reached the point where replacement is necessary.
The sports-bottle-type bacteriological filters, available from Katadyn or Berkey, are a good,
low-cost alternative for storing in the trunk of your car for emergencies, or to carry on day
hikes, backcountry runs, and so on. They are also useful as a backup in case the pump on your
primary water filter breaks.
Significant Use, Portable
I recommend using a filter with a cleanable ceramic cartridge and a carbon core, such as the
Katadyn Combi Filter ($140), MSR MiniWorks ($90), or the MSR WaterWorks II ($145).
