SteriPen (C) Daniel FriedmanHow to Select & Use a Portable UV Light to Purify or Sterilize Drinking Water
     

  • UV WATER DISINFECTION, PORTABLE - CONTENTS: Steri-PEN® classic, portable "hand held" water purifier uses UV light. Solardyne portable solar-powered UV water sterilizer. Choices of types of drinking water filters & sterilizers. How to select & use a water filter for portable or emergency drinking water supply
  • POST a QUESTION or READ FAQs about buying & using a portable UV light as a water purifier - what can these devices accomplish and what potential hazards might remain?
  • REFERENCES

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Effectiveness of UV lights to purify water: This article explains portable or handheld UV-type water purification systems that can be used to sterilize water for drinking purposes. Portable drinking water sterilizers: this article series outlines methods to purify or sanitize drinking water in an emergency following a disaster such as an earthquake, flood, or hurricane.

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Guide to UV Lights for Emergency Water Purification

The good news is that while some emergency drinking water "purification" methods do not handle all or even some common and important contaminants, there are types of water filters and water filtration systems that can treat water containing various microbes including bacteria, Giardia, and Cryptosporidium cysts, as we discuss in this article series and beginning below.

Portable UV Light Sterilizers for Emergency Drinking Water - the SteriPEN®

SteriPen (C) Daniel FriedmanThe SteriPen® Classic is a portable UV water purifier that can treat a liter of water, using ultraviolet light, in 1 1/2 minutes.

The manufacturer informs consumers that UV light destroys viruses, bacteria, and protozoa. The microbes covered by this description include Cryptosporidium, viruses, bacteria, and Giardia, and also E. coli, Salmonella, Staph, and Strep.

[Click to enlarge any image]

The SteriPen® works by combining a battery-operated UV light combined with a mixing wand that is inserted into a container of water. The SteriPen weighs 5.7 oz, and as you can see even in our package photo, it is quite compact.

To operate the SteriPen® the user uses a slide switch to select the volume of water to be treated and to turn on the device. The UV lamp-end of the Steri-Pen is inserted downwards into "clear water" (see our warnings below), and the water is stirred until the indicator light (basically a timer) turns green.

SteriPEN, produced by Hydro-Photon, is also available as a Traveler Mini (weight, 3.6 oz, capacity: 1/2 liter of water in 48 seconds) and the Adventurer Opti (3.6 oz., 100 treatments per battery, rechargeable model and solar-recharging case available).

Hydro Photon describes the SteriPEN (portable UV light water treatment system) as treating water containing these microorganisms:

  • Bacteria (including wide range of species)
  • Campylobacter (cause of bacterial diarrhea)
  • Cholera
  • Cryptosporidium (cyst containing protozoan parasites)
  • Escherichia coli (E. coli) strains (E. coli O157:H7) causing illness (such as in sewage contaminated water supply)
  • Hepatitis
  • Legionella bacteria -
    see HOT WATER ANTI-SCALD REGULATIONS for a discussion of the development of leginella bacterial contamination in water heaters & geyers
  • Protozoan parasites
  • Salmonella
  • Shigella (presumably Shigella sonnei)
  • Viruses

What important water contaminants were not found in this list?

Other common drinking water contaminants might be addressed but were not listed in the above and are also not listed in the description of larger-capacity UV light treatment drinking water disinfection systems discussed separately at UV ULTRAVIOLET LIGHT WATER TREATMENT.

  • Amoebic cysts was not listed. See Chang (1985)
  • Bacillus subtilis spores
  • Cysts of the protozoan Acanthanieba castellani
  • Enteric viruses poliovirus type 1
  • Giardia was not listed? Why not? See Giardia Limitations below
  • Simian rotavirus SA11
  • Streptococcus faecalis
  • Staphylococcus aureus
  • Typhoid was not listed ? Why not? [Citation needed]

Watch out: Factors that affect the effectiveness and operating time of any UV light used to treat water in an effort to make it potable, or at least improve its potability include at least the following:

  • What contaminants are present in the water. UV treatment does not address chemical contaminants, nor do some water filters.
  • The water temperature. (The SteriPen includes a temperature sensor)
  • The water clarity - the level of particles in the water and particle size have important effects on the UV disinfection process

    Qualls (2008), in a study discussing the advantages of UV light as an alternative to chlorination, point out that filtration is often necessary to reduce the level of suspended particles in water for UV treatment to be effective. Abstract excerpts:

    It is well known that aggregation of bacteria and viruses provides some degree of protection from halogen and ozone disinfection. Adsorption of microbes to inorganic surfaces such as clay provides little protection. However, organic particles can protect organisms from disinfectants and can become a major limiting factor in disinfection. Particulate materials also effect [sic] UV disinfection.
  • Clays do little to inhibit UV disinfection because they tend to scatter UV light rather than absorb it. Oilver and Cosgrove attributed the difference between microbial survival in irradiated raw wastewter and secondary effluent to differences in particle sizes. They believed that bacteria inside aggregates of particulate matter were at least partially protected from UV light. They found that a sample dispersed by ultrasonication was more sensitive to UV disinfection.

As we discuss in more detail at UV ULTRAVIOLET LIGHT WATER TREATMENT, the proper UV light selection for water treatment is critical in the success of this approach. The UV light must have been properly selected to handle the volume and flow rate of the water supply where it is installed.

If ultra violet light is not of sufficient capacity to treat water flowing past its bulb it will not be effective. Therefore it is important to follow the manufacturer's instructions when using the SteriPen UV light portable device.

Portable UV Light Sterilizers for Emergency Drinking Water - Solardyne Portable Solar Powered UV Water Sterilizer

Solardyne makes a portable UV light system for treating drinking water, comprised of a battery-operated UV light through which water may be run for treatment. The battery is re-charged by a solar panel.

The Solardyne portable UV water treatment system is indeed movable, and in fact comes on wheels. It is not suitable for backpacking or lightweight camping however. Rather the solar powered UV light system is intended for treating water at remote camps, work sites, and for disaster or emergency response field use.

UV Light Effectiveness Against Giardia Cysts Questioned by Expert

UV Light & Giardia: Although the SteriPen producers describe this device as handling Giardia in water, not all sources agree that UV light will reliably and effectively kill cysts.

Watch out: Dr. Omar Amin, of the Tempe AZ Parasitology Center]. Websites that advertise use of UV light to kill giardia may be misleading. UV light will kill Giardia trophozoites but the real concern for drinking water is the cysts, since it is the cysts from stool that appear there. Other treatment methods may be needed if Giardia is present in the water supply.

Linden (2002) commented in separate research that in our OPINION does not appear to obviate Amin's warning:

The human and animal pathogen Giardia lamblia is a waterborne risk to public health because the cysts are ubiquitous and persistent in water and wastewater, not completely removed by physical-chemical treatment processes, and relatively resistant to chemical disinfection.

Given the recently recognized efficacy of UV irradiation against Cryptosporidium parvum oocysts, the inactivation of G. lamblia cysts in buffered saline water at pH 7.3 and room temperature by near monochromatic (254 nm) UV irradiation from low-pressure mercury vapor lamps was determined using a “collimated beam” exposure system. Reduction of G. lamblia infectivity for gerbils was very rapid and extensive, reaching a detection limit of >4 log within a dose of 10 JM-2.

The ability of UV-irradiated G. lamblia cysts to repair UV-induced damage following typical drinking water and wastewater doses of 160 and 400 JM-2 was also investigated using experimental protocols typical for bacterial and eucaryotic DNA repair under both light and dark conditions. The infectivity reduction of G. lamblia cysts at these UV doses remained unchanged after exposure to repair conditions. Therefore, no phenotypic evidence of either light or dark repair of DNA damage caused by LP UV irradiation of cysts was observed at the UV doses tested.

We conclude that UV disinfection at practical doses achieves appreciable (much greater than 4 log) inactivation of G. lamblia cysts in water with no evidence of DNA repair leading to infectivity reactivation. - Linden (2002)

UV light for water disinfection where Giardia is present has, however, been successfully used in combination with chlorination as an approach to killing Giardia in water.

Watch out: OPINION: if the water you are treating is visibly dirty or murky, there is a significant risk that the UV light will not penetrate and act on microorganisms in the water nearly as rapidly, and additional pre-filtering steps and/or extended treatment time may be necessary.

Permanently-Installed UV Lights Installed on Private Well Water Systems

UV light on well and pump system (C) Daniel FriedmanUV Lights for water purification: UV Lights are not filters. UV lights for drinking water treatment are installed in some properties as a means to kill bacteria in a water supply.

We do not anticipate that UV light systems will be working in a disaster area, and we are doubtful that one can rely on this process for emergency drinking water purification: even if a UV light system is working, it will at kill bacteria and similar pathogens only.

But if emergency generators or emergency electrical power are being provided to run a local water pump intended to provide drinking water, be sure that power is also provided to the UV light or to any other water treatment equipment that is installed in your location.

Watch out: OPINION: if the emergency event that has led to loss of power and water included a severe storm or flooding or other event that has sent ground water or flood waters into a private well, that water may be contaminated with chemicals or other ingredients that were never anticipated by water treatment equipment already installed at a building.

Therefore even if you return a private well and water treatment equipment to operation, the water may not be safe to drink. Seek advice from local emergency management authorities before drinking water from any water source following an emergency, and to be safe, until you get an "OK" on using local water sources, you'll want to rely on suitable portable water purification methods.

A UV light water treatment system will not remove chemical contaminants in a water supply.

See UV ULTRAVIOLET LIGHT WATER TREATMENT for details of residential type UV light water treatment systems as well as a discussion of when such systems are useful and appropriate.

Watch out: UV Light & Giardia: UV light does not kill cysts, according to Dr. Amin. Websites that advertise use of UV light to kill giardia may be misleading. UV light will kill Giardia trophozoites but the real concern for drinking water is the Giardia cysts, since it is the cysts from stool that appear there. Other treatment methods may be needed if Giardia is present in the water supply.

UV light for water disinfection where Giardia is present has, however, been successfully used in combination with chlorination as an approach to killing Giardia in water.

Also see LIGHT, GUIDE to FORENSIC USE.

 

Continue reading at VEGETABLE DISINFECTION or select a topic from the More Reading links shown below.

Or see UV ULTRAVIOLET LIGHT WATER TREATMENT for a discussion of UV light disinfection on building water supply systems.

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UV WATER DISINFECTION, PORTABLE at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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