Frequently Asked Questions

1. Does SteriPEN™ use chemicals to purify water?

SteriPEN™ disinfects only with light — it adds no chemicals to the water. By not using chemicals, SteriPEN™ avoids problems of chemical toxicity and unpleasant chemical taste.

2. What is ultraviolet (UV) light?

Ultraviolet light is invisible, high-energy light.

Wavelengths of light are measured in nanometers (nm). A nanometer is one billionth of a meter. Visible light ranges from red at about 700nm to violet at about 400nm. Normally the human eye does not see light at wavelengths outside of this 400nm to 700nm “visible” range.

The entire band of UV light is about as broad as the entire visible spectrum — it runs from 400nm to about 100nm. The UV band is divided into 3 ranges: UV-A between 400nm and 320nm, UV-B between 320nm and 290nm and UV-C between 290nm and 100nm. Most of SteriPEN’s light is emitted at 254nm, in the UV-C range. (See item #3 for discussion of SteriPEN’s visible light.)

3. How does UV purify water?

UV light destroys DNA and thereby prevents microbes from reproducing.

Germicidal UV light – between about 240nm and 290nm – acts on thymine, one of the four base nucleotides in DNA. When a germicidal UV photon is absorbed by a thymine molecule that is adjacent to another thymine within the DNA strand, a covalent bond or dymer, between the molecules is created. This thymine dymer prevents enzymes from “reading” the DNA and copying it. Without the ability to replicate DNA, the microbe cannot reproduce and is rendered harmless.

4. Is UV light dangerous?

Exposure to ultraviolet light can cause skin and eye damage. Used as directed, SteriPEN™ will not cause UV exposure to the user. Note that SteriPEN™’s lamp emits a number of wavelengths, some of which are in the visible range. The visible blue light given off by SteriPEN™ is just that, visible blue light – not ultra violet – and it is not dangerous to look at. In fact while the visible light has no germicidal effect, it is an important indicator that the lamp is functioning properly. If no light is visible the lamp is malfunctioning.

UV-C will not pass through most materials. Drinking containers made from glass, ceramic, metal, and nearly all plastics block UV-C transmission. Also, the underside of the air/water interface in a water container acts as a very effective reflector for UV-C. As a result, when SteriPEN™’s lamp is immersed in virtually any drinking vessel, the UV-C is well contained. Note that SteriPEN™’s water sensors prevent it from operating unless the lamp is completely immersed.

While very few materials are transparent to UV-C, there are a small number of uncommon materials that are. These include optical grade quartz (the SteriPEN™ lamp material) and a few fluoropolymers in the Teflon family – both unlikely materials to be used for drinking containers.

5. How does SteriPEN™ operate?

SteriPEN™ has an onboard microcomputer that controls dose times. The user must decide on one of two volume ranges to be treated – either 16 oz or less or between 16 oz and 32 oz. Once volume has been indicated by either one button push or two, SteriPEN™ automatically delivers the appropriate dose duration and then shuts off. There is no need for the user to time anything.

SteriPEN’s™ dose time ranges from 38 to 48 seconds for 16 ounces to 90 seconds for 1 quart (or 1 liter). This is far faster than chemical treatments that can take up to 4 hours. SteriPEN™ is also generally quicker – and certainly far easier – than pump filters. It is also worth noting that SteriPEN’s™ speed and ease of operation makes it useful in places where filters and chemicals are inappropriate such as restaurants and cafes.

6. Is it important to agitate the water?

During a SteriPEN™ treatment it is important to agitate the water by stirring with the SteriPEN™ or gently shaking the water in the container. Agitation of the water insures uniform UV treatment in a way that cannot be achieved in stagnant water.

7. Can SteriPEN™ purifiers treat turbid, murky, or cloudy water?

SteriPEN™ Handheld Water Purifiers are intended for use, and are most effective, in clear water. With that said, SteriPEN™ purifiers have been proven to reduce microbial contamination in turbid water as well. If clear water is not available, first try to filter the water to clarify it. SteriPEN™ sells a pre-filter to accomplish this task and people have used a variety of other methods from household coffee filters to nylon hosiery to remove particulates. If time permits, allowing the suspended solids to settle to the bottom of a container and then pouring off the clear portion of the water into a separate container also accomplishes the task. Once clarified, use the SteriPEN™ normally.

If clarification is not possible and it is necessary to treat turbid, murky or cloudy water such as in an emergency situation, use SteriPEN™ as follows:

To treat 1 liter of turbid water, use two one-liter treatments. Push the operating button once, complete that treatment and then push the operating button once again and complete the second dose.

To treat 0.5 liters of turbid water, use one one-liter treatment. Push the operating button once and complete the treatment.

In other words, when confronted with turbid water, use double the amount of UV light. Unlike chemicals, using twice as much UV light is not harmful.

For more detailed testing information, visit our testing page.

SteriPEN™ should also not be used to treat liquids other than water as such liquids may allow very poor UV-C transmission and therefore reduced germicidal effectiveness.

8. What kind of batteries does SteriPEN™ use?

SteriPEN™ uses four AA batteries. The number of doses between batteries is dictated by battery type. Standard alkaline AA’s provide anywhere from 20 to 40 16-oz doses. Lithium disposable camera-type batteries give about 140 16-oz doses but do not function well in cold temperatures. Nickel Metal Hydride (NiMH) rechargeable batteries are a great all-around choice. While slightly heavier than the other types, they perform well in cold temperatures and provide about 150 16-oz doses at temperatures above 32°F. The NiMH batteries add great economy, too, as they can be recharged hundreds of times – even with solar chargers.

9. What is the microbiological effectiveness of SteriPEN™?

SteriPEN™’s microbiological effectiveness has been tested at 3 universities (U. Maine, U. Arizona, Oregon Health Sciences U.). Used as directed, SteriPEN™ has been shown to destroy over: 99.9999% of bacteria, 99.99% of viruses and 99.9% of protozoa (i.e. Giardia and Cryptosporidium). These levels of destruction exceed the requirements of the US EPA’s Guide Standard and Protocol for Testing Microbiological Water Purifiers.

10. Is SteriPEN™ Certified?

SteriPEN™ has been tested by Intertek Testing Service to all relevant US and international standards. SteriPEN™ conforms to: UL Standard UL 61010B-1, Conforms to EN 61010-1: 1993 + A1 + A2. Certified to CAN/CSA C22.2 No. 1010.1-92, Listed 3058969