Don't assume that water at a campground is safe to drink, even if it comes from a spigot. The water in lakes, rivers, and springs may look crystal clear but often contains various bacteria that can cause illness.
Unless it is posted or an official from the campground has told you that the water is safe to drink, you must use one of three purification methods: filter, chemical tablets, or boiling.
- Filters: With a filter, you simply pump water from the source into a container. The filter mechanically removes protozoa and bacteria, and you are good to go. If the filter also has an iodine system built-in, it will kill viruses too.
- Chemical tablets: Water purification tablets, such as Potable Aqua, are a second option. They employ chemicals, usually iodine, to kill harmful bacteria. Tablets are easy, inexpensive, and quick, but can affect the taste of the water. Tablets also have a limited shelf life — six months once the bottle is opened.
- Another concern is that chemicals are ineffective against some protozoa, such as cryptosporidium, and require much longer to work if the water is full of sediment or is very cold.
- Boiling: Bringing water to a rolling boil is a third option. Boiling has no effect on taste. But it has drawbacks as well. Boiling water is time-consuming, must be done in small batches, requires pouring hot water into containers and then waiting for it to cool, and uses up fuel.
Just because your backcountry water appears pure doesn't make it safe. Teensy vermin like giardia and cryptosporidium can cause nausea, diarrhea, vomiting, or worse, and you'll never see 'em coming. A water filter is a must-have for outdoor travel.
Portable water filters
These days, there's really no excuse for going without a filter: Handheld filters are getting more compact, lighter, and easier to use, and you can find filters ranging in price from $25 up to $300. Unless your needs are very basic indeed, filters in the $50-and-up range offer more versatility and far more durability and function than their cheaper counterparts.
A filter's purpose is to strain out microscopic contaminants, rendering water clear and somewhat pure, depending on the size of the filter's pores — what manufacturers call pore-size efficiency. A filter with a rating of one micron or smaller will remove protozoa like giardia and cryptosporidium, as well as parasitic eggs and larvae, but it takes a pore-size efficiency of less than 0.4 microns to remove bacteria. (A micron is one thousandth of a millimeter — you can't see it with the naked eye.)
A good backcountry water filter weighs less than 20 ounces and is easy to grasp, simple to use, and a snap to clean and maintain. At the very least, buy one that removes protozoa and bacteria. (A number of cheap, pocket-sized filters remove only giardia and cryptosporidium, so buying one of these is risking your health to save money.) Consider the filter's flow rate, too: A liter per minute won't leave you dying for a drink.
If you travel in Third World countries, or if any water you encounter may be contaminated by sewage, viruses are a concern. Only one filter, the First Need filter by General Ecology, claims to meet EPA virus-removal standards by filtration alone, thanks to a fancy matrix system — a convoluted maze of passages that trap little nasties inside.
The other filters require chemical assistance, either by incorporating iodine into the filter or using iodine tablets like Potable Aqua. Iodine tastes awful and can be a health risk to some people, so many filters employing it also have a carbon element that removes the iodine when its job is done.
Carbon also gets rid of pesticides, herbicides, heavy metals, and chlorine, but there are a couple of carbon-use caveats:
- A few recent studies have shown that in certain situations, it's best to leave a little iodine in the water. If you think that your water source is contaminated with sewage, remove the carbon filter. Orange juice crystals (ascorbic acid) can help offset the iodine's nasty taste since ascorbic acid oxidizes or neutralizes the iodine.
- If you follow this lead, remember to wait 30 minutes after filtering the water before stirring in the crystals. Thirty minutes should be enough contact time for the iodine to kill even the most sturdy of microorganisms.
Folks suffering from thyroid disease, immunodeficiencies, and iodine allergy should not use iodine. Pregnant women should not use iodine for longer than one week.
All filters will eventually clog — it's a sign that they've been doing their job. If you force water through a filter that's becoming difficult to pump, you risk injecting a load of microbial nasties into your water bottle.
Some models can be brushed or scrubbed to extend their useful lives. And if the filter has a prefilter to screen out the big stuff, use it: It will give your filter a boost in mileage, which can then top out at about 100 gallons per disposable element.
Because a filter's carbon element can reach its limit for absorbing a particular chemical and then let bad stuff through, always replace the filter and the carbon element according to the manufacturer's recommended schedule.
Because each filter has its own idiosyncrasies and care needs, be sure to read a manufacturer's use instructions carefully.
Purifying water without a filter
If you don't feel like carrying the weight or bulk of a filter, you can opt for chemical treatments such as iodine, or you can boil the water. Boiling is virtually foolproof; however, it does take a fair amount of time and a considerable amount of fuel. Additionally, not many people enjoy drinking hot water on a hot day.
Thus, iodine, Polar Pure (an iodine crystal-based system), or Potable Aqua (a tablet) may be the way to go. Because Potable Aqua is a tablet system, it is quite easy for children to understand and use if necessary, although it does have a very limited shelf life once the bottle is open. Polar Pure has a much longer shelf life and is more versatile, but may be more complicated to use.