SteriPEN Water Purifier
Zap water bugs with UV light
Stick the SteriPEN unit
into a glass of water, turn it on, stir it around, and in
45 seconds you have killed any bacterial
contamination, leaving you with clean safe drinking
It is a
great way to discreetly purify the glass of water at your
table in a third world restaurant, and has many other uses
Part 1 of a series on
SteriPEN products. Part 2
reviews the Traveler and
Part 3 reviews the solar charger.
The SteriPEN is a space age
unit that purifies water quickly and simply, using UV light.
It is compact, light weight
and easy to use, and is probably the most effective solution to
ensuring the water you drink is safe.
Who Needs a SteriPEN
Hikers and campers
If you go hiking in the
backwoods, you'll probably take some sort of water filtration
device with you. We all need lots of water, and it is,
alas, both bulky and heavy to carry with us.
Unfortunately, those lovely
looking fresh country streams are often dangerous to drink from,
due to the presence of 'coliform matter' caused when runoff water
from wildlife excrement contaminates the water with dangerous
and potentially lethal bacteria.
A Steripen is small and
lightweight and a great way to ensure you can enjoy safe
drinking water when hiking.
One of the blessings of our
modern lives is that we have reliable safe water freely flowing
from our taps at home (but see the next point). This is
not nearly so assured in the rest of the world, and
treating the water you use, even for brushing your teeth, in
your hotel room and elsewhere with the Steripen can ensure your travel pleasures aren't disrupted by inconvenient and
sometimes serious illnesses from water-borne pathogens.
An unexpected danger can
also lurk, in some countries, in supposedly safe bottled water.
In some countries, there are no quality standards for bottled
water and you might find yourself paying a premium for water no
better than what comes out of the tap. The Steripen can be
inserted into a bottle of water to sterilize the water before
you drink from it.
Because the Steripen is
small and simple to use, it can also be used to discreetly
purify a glass of water given to you in a restaurant when you're
unsure how safe the water might be.
Everyone for their Emergency
What would you do if your
city's water supply was disrupted? Perhaps an earthquake,
or an act of terrorism, or system failure might suspend one of life's essentials
we take for granted in most western countries - the reliable
flow of safe water through our taps. Indeed, simple mistakes have also disrupted water flow or water purity,
sometimes for days at a time, and in some of the world's most
If you like to be prepared,
a SteriPEN is an excellent addition to your Emergency
Disaster Preparedness Kit. It has a virtually unlimited
shelf life (many regular water filters expire after a few years
whether used or not)
and as long as you can feed it batteries, the 5000 uses per
replaceable lamp unit give you plenty of pure clean water in an
The Steripen is sold attractively
packaged in a plastic cylinder. Inside is the unit
itself, which comes complete with a strong protective sleeve to
fit over its lamp when not in use, plus a nice carry pouch.
A set of well written instructions and warranty/registration
card complete the package.
The Steripen needs four AA
batteries, but, alas, no batteries are supplied with the unit.
You don't get much for your $80 these days.
Although skimping on
batteries, the manufacturer is generous with the warranty,
offering a 'limited lifetime' warranty. In the fine print,
it reveals you must send in the registration card to
qualify for the warranty, and the warranty is offered to
the original purchaser only.
Because the lamp must be
replaced every 5000 uses, the warranty of course covers the lamp
only for its 5000 use life, but the body warranty is unlimited.
The unit, complete with
protective cover, weighs 3.6 oz. Add a set of batteries
and you've about doubled the weight.
How it Works
The Steripen uses
ultra-violet (UV) light (better to use the term 'radiation'
rather than light, perhaps) to sterilize the water. UV
light is the same type of radiation that causes sun-burn, and,
in large doses, skin-cancer. The same dangerous properties
of the light are put to good use with the Steripen to simply
kill any bugs and germs that might be in the water.
UV radiation is used by many
town water supplies to sterilize their water. It is an
accepted, safe, and reliable solution, and although we're using
the term 'radiation' it is nothing like radioactive radiation
and water that has been exposed to UV light is totally safe in
Although direct UV light is
dangerous to people as well as to bacteria, by a happy trick of
nature, the UV light is completely contained within water, and
so you're at no risk when using the Steripen. You can see
a blue glow, but this is not UV light (which is invisible) but
visible light that is also generated at the same time.
More than 90% of the output of the unit is in the form of
invisible UV light.
The Steripen does not
neutralize any poisons or other bad chemicals. It kills
living things, but doesn't do anything to inert poisonous
Neither does it precipitate
out any suspended solids, such as in a glass of
muddy water. In fact, if the water is not clear, the UV
radiation does not penetrate as efficiently through the water
and the Steripen will not work as reliably. For this
reason, the instructions say to only use it with clear water,
and if the water is muddy, you should let the water settle
first, or pre-filter it.
The Steripen has two
settings - one for up to 16 ounces (one pint) of water, the second for up
to 32 ounces (one quart). You simply choose the appropriate setting,
turn it on, stick the light tube 'wand' into the water, stir it around until the UV light goes off, and you then have
pure safe water to drink.
Electronics inside the unit
compute how long to operate the UV lamp for, and generally it is
about 45 seconds for 16 ounces and 90 seconds for a full 32
ounce quart of water.
The unit also counts how
many times it is used. Because the UV light tube wears out
over time, when the unit has been used 5000 times, it gives an
error and requires you to replace the light tube. This
involves returning the unit to the factory, where they replace
the assembly and return the unit for a $40 fee. The unit
gives a warning at 4900 uses so you can plan for the replacement
at a convenient time.
Using the Steripen
Using the Steripen is as
simple as it should be.
Because you need to fully
immerse the light tube, there should be at least 2½" of water in
the water container, although if the container were flat and
wide, you could hold the Steripen on its side to fully cover it.
You push its button, then
immerse it in the water. The unit senses when it is in the
water and activates.
As well as generating the UV
light which is invisible, it also generates some visible light
so you can see that the unit has started to work (and, more to
the point, when it has completed its task, too).
Stir it around while it is
radiating, and when the light turns off, check that the
indicator LED shows green.
And that's all you need to
know and do. Almost instant safe drinking water is the
I was concerned that the
glass capsule surrounding the light might break, but Miles
Maiden, Steripen's inventor and company President, explained the
capsule is actually made from strengthened quartz, 1/10" thick.
It is strong and unlikely to break during normal usage, which is
just as well, because the warranty unfortunately excludes glass
When not in use, a strong
plastic sleeve surrounds and protects the quartz tube.
Because ice cubes are often
not perfectly clear, the UV light may not be able to shine all
the way through ice and so you should not have ice in the water
when purifying it.
The Steripen uses a lot of
power and is fairly hard on batteries. A set of four
regular AA alkaline batteries will be good for about 20 - 40
uses, each for a pint of water.
If you get the longer life
Lithium type batteries (single use, not to be confused with
Lithium Ion rechargeables), these can give you up to 140 cycles.
Rechargeable batteries are
probably your best choice if you plan to use the unit regularly.
A set of modern high capacity NiMH batteries (such as the ones
here) can be expected to give 150 uses per charge. The
cheaper NiCad type batteries will give fewer than 20 uses per
charge and probably shouldn't be used.
The Steripen tells you when
the batteries need replacing (the LED flashes red quickly).
The Steripen compared to other
If you're comparing the
Steripen with other ways to get safe drinking water, it is first
essential to compare it accurately with similar products.
Many devices are sold as
water filtration systems, but these are not the same as
an EPA approved water purification system (the Steripen
has been independently tested and passes the EPA's purification
The best water filtration
systems have a maximum filter size of 0.2 microns (a micron is a
millionth of a meter) and are effective against bacteria (which
range in size from about 0.2 microns up to 10 microns) but are
ineffective against viruses which are much smaller (0.004 - 0.1
microns in size).
A purification system is
effective against both viruses and bacteria. Viruses (eg
hepatitis) are every bit as dangerous as bacteria, and so you
really need a full purification system rather than the partial
solution presented by a filtration system.
Filtration systems not only
don't protect you from viral infection, but are also can be more
expensive than the Steripen, bulky, and awkward to operate
(probably requiring you to pump water forcefully and slowly
through a filter). Filtration systems are also prone to
clogging, and either need regular replacing or cleaning.
The lowest tech approach to
purification is to simply boil your water for several minutes.
But this requires a heat source and suitable container to boil
the water in, plus the patience to wait until the water has
cooled again before drinking it.
The most common purification
method is to add chemicals to the water that will kill the
viruses. Chlorine or iodine tablets are added to the
water, and after letting it stand for a while (up to four hours
in some cases) you end up with water that is safe to drink, and
which hopefully doesn't taste too bad.
The Steripen is generally
quicker, easier, and more portable than all these other
Which SteriPEN Model is Best
When this review was first
written, in December 2004, this was the only model SteriPEN
Since that time, not only
has the price of the original (we term it the 'Classic')
SteriPEN dropped from $150 to $99.95, but the manufacturer has
also released a new smaller model, currently priced at $130.
All models work identically, the only difference is their size
and price. We review the
new Adventurer and Traveler model SteriPENs here.
Update November 2007 :
Another price drop, just in time for the Christmas season - the
Classic SteriPEN is now only $79.95, and the two new units have
dropped to $99.95. Wow! Both types of unit are now
very aggressively priced.
The Classic SteriPEN is less
expensive, but is also bulkier and heavier than the new Traveler
and Adventurer model SteriPENs.
With airlines increasingly
reducing the amount of luggage you can take with you for free,
and with weight and space considerations also being critical for
backpackers, the smaller and lighter units more than justify the
$20 extra cost for most people. But if your main use for
the SteriPEN is to have it as part of your disaster preparedness
kit, you might prefer the Classic SteriPEN which uses very
common AA batteries.
Where to Buy
Steripen is manufactured by
Hydro-Photon in the US. They have retail distributors
spread around the US, and these days the device lists for a very
good value of $79.95 (it was originally $150).
Hydro-Photon forbid discounting.
Travel Essentials stock the full range of SteriPEN products
and accessories, and offer the Classic at this price,
with no sales tax and give you free shipping, which is probably
the best deal available. And should you want to buy more
than one, they offer a $5 per unit discount on multiple orders.
They also offer the
Adventurer units at $99.95 each.
Chances are, before reading
this article, you didn't know you needed a water
purifier, or what the difference is between a water filter and
But whether you now feel
this might be useful when hiking outdoors, when traveling
overseas, or just to keep in your household emergency kit, you
probably now agree that a Steripen is a very convenient and
effective solution to the problem of how to ensure you have
reliable access to safe drinking water, wherever you are.
The Steripen is now a
regular part of my international travel kit. Recommended.
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17 Dec 2004, last update
21 Jul 2020
You may freely reproduce or distribute this article for noncommercial purposes as long as you give credit to me as original writer.