The SteriPEN ultraviolet water treatment system is a popular choice for backpackers and day hikers because it’s easy to use, fast, lightweight, and doesn’t leave any aftertaste in your water like chemical treatments. But like all backcountry water treatment solutions, it has its PROS and CONS, and is not suitable in all circumstances.
|Neutralizes biological organisms||Does not work with all bottles or reservoirs|
|Very fast||Battery dependent|
|Non-mechanical, no pumping||Does not remove chemical or mineral contaminents|
|Effective in cold or freezing weather||Not effective with cloudy or murky water|
|Does not affect taste||Does not neutralize larger organisms, i.e. worm eggs|
What kind of contaminants occur in backcountry water?
Backcountry water can contain two different types of contaminants that can make your ill: biological organisms and mineral or chemical contaminants, including agricultural or industrial runoff. Not all sources or regions suffer from both, so it’s best to do some research about water quality and the need to treat your water before hiking or backpacking in a new area. Contacting the local land manager, like the US Park Service, US Forest Service, or state authority that administers the land is usually a good place to start. Local guiding services and hiking clubs are also useful sources of information.
What kinds of contaminants is the SteriPEN effective against?
The SteriPEN protects you against many microscopic biological contaminants, including:
- Protozoa, including Giardia and Cryptosporidium which cause severe diarrhea. Giardia, often called beaver-fever, is the most common form non-bacterial diarrhea in North America. There are over 1 million cases of Giardia reported in the United States each year with the highest rate of occurrence in New England and Alaska, according to the CDC.
- Bacteria, including Campylobacter, E. Coli, Salmonella, and Shigella.
- Viruses, including Hepatitis.
What about mineral or chemical contaminants and industrial pollution?
The SteriPEN does not neutralize or remove mineral or chemical contamination from agriculture and industry, including herbicides, pesticides, and fertilizers. You will need a water purifier like the General Ecology First Need or MSR Guardian which are designed (and certified by the EPA) to remove them if they’re a concern.
How does a SteriPEN Work?
A SteriPEN is an ultraviolet light that you immerse in a bottle of water that “neutralizes” 99.9% of the viruses, bacteria, and protozoa found in backcountry water sources. A SteriPEN doesn’t actually kill these organisms. Instead it damages their DNA so they can’t reproduce in your gut and overwhelm digestive or immune system. It’s a subtle but important difference.
What water bottles is a SteriPEN compatible with?
SteriPENs work with a wide variety of variety of bottle and containers, but be sure to read the directions that come with your unit or contact the company if you have any questions. While SteriPENs do work with hydration reservoirs it’s important that you not try to purify more than one liter of water at a time, since most hydration reservoirs are larger than one liter. It’s also important to separate the tube from the reservoir at the time of treatment, otherwise water can flow into the tube, avoiding treatment. When in doubt, your best bet is to use a SteriPEN with a wide mouth half-liter or one liter bottle from Nalgene, which is sure to work.
Does the SteriPEN purify water left on the bottle threads?
When you fill a bottle in a pond or stream, some of the water is bound to adhere to the bottle cap threads, and this water will not be purified by the SteriPEN. Instead, the manufacturer of SteriPEN recommends drying the bottle threads with a towel before drinking. Even then, there’s still a risk that microscopic organisms will remain. Most people have a strong enough immune system that they can resist a small dose of organisms, if any are present. The same can’t be said if you were to ingest a full liter of contaminated water. If you have a compromised immune system or it’s still a matter of concern, use a different water filtering and purification method.
How much water can you purify with a SteriPEN?
The number of liters you can purify varies by model, as shown in the table below. While battery life is good on SteriPENs, it’s worthwhile to carry a backup batteries or a USB recharger in case your unit runs out of power during a trip. For units that require AA batteries, SteriPEN recommends using Lithium batteries because they will not freeze, unlike Alkaline batteries which contain a water based electrolyte solution.
|Model||Batteries||Liters Treated / Batteries or Charge||Weight w/ Batteries|
|Steripen Classic||AA (4)||Lithium: 150||6.3 oz.|
|Steripen Ultra||USB-only||Full Charge: 50||4.9 oz.|
|Steripen Freedom||USB-only||Full Charge: 50||2.6 oz.|
|Steripen Opti Adventurer||CR123 (2)||CR123: 50||3.8 oz.|
|Steripen Aqua||AA (4)||Lithium: 150||6.3 oz|
Can a SteriPEN neutralize tape worm eggs?
The company that manufactures SteriPEN has not tested their products for efficacy against worms eggs. I would suggest you play it safe and use a filter instead.
Can you only use a SteriPEN to purify clear water?
A SteriPEN should only be used to treat clear, non-murky water, without floating sediment. SteriPEN sells a pre-filter which can be used to clarify water if it is murky.
What about reddish, highly tannic water?
If the water has a high-tannin concentration, the SteriPEN will not be effective. If you can filter your water to something that can be described as a light iced-tea, or a light lemonade, then you can treat that volume of water twice with the SteriPEN.
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