 |
InspectAPedia® |
InspectAPedia
|
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair | Ask a Question or Search InspectAPedia |
Here we explain and help choose among the types of portable water purification filters that can be used to sterilize water for drinking purposes when traveling, camping, and in emergencies when the normal water supply is not available or is not sanitary. Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman. Guide to Use of Filters for Drinking Water Purification
This article series outlines methods to purify or sanitize drinking water in an emergency following a disaster such as an earthquake, flood, or hurricane. A companion article, DRINKING WATER - EMERGENCY SOURCES,describes possible sources of drinking water that may be useful in emergency conditions. See WATER TREATMENT EQUIPMENT CHOICES for details on other water treatment options. The good news is that 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 just below. If you are looking for information on home water filters to be installed on plumbing systems in regular use, such as filters used to remove dirt, silt, sediment, iron, and odors from well water, see WATER FILTERS. Ceramic water purifying filters for Water Purification TreatmentPurifying filters use materials such as ceramic filters which have extremely fine pores to filter out harmful bacteria and protozoa. Examples of portable ceramic water filters include the Katadyn® ceramic water filter, Hiker Pro Micro Filter (also from Katadyn), and ExsStream ceramic water filter. Our portable, hand-operated pump-type water filters shown below include the Katadyn® Hiker microfilter (below left) and the Minworks® EX Microfilter.
Portable water filters all include a pump, usually a manual or hand pump, which forces water through a very fine ceramic filter cartridge, delivering a clean, if slow stream of potable drinking water. Some portable water filters include a container into which water is poured, then pumped out. Note on Portable Water Filter Cartridge Types: There are several types of filter cartridge designs, among which in our OPINION the most significant distinction is between fiberglass/paper/charcoal type filters and ceramic filters. The latter, ceramics, can be expected to have a longer use-life and can be cleaned and restored in the field. If you care, be sure to check the type of filter used in the specific model of portable water filter you are considering, as several manufacturers offer more than one filter type across their model line.
A replacement filter for the Katadyn Hiker/Hiker PRO, and Base Camp filter models is shown at left. The Katadyn Hiker water filter uses a 0.3 micron pleated glassfiber (fiberglass) filter with an activated charcoal core to remove bacteria, cysts, and sediment (Klebsiella terrigena, Giardia, and Cryptosporidium). One filter is rated for up to 750 liters of water (250 gallons), or less, depending on the clarity of the starting water being filtered. The device weighs 11 ounces and is 6.5" x 3". without including the tubing or accessories. Katadyn produces three groups of water filter products: an Endurance Series (higher capacity, extreme use conditions, can handle highly turbid (murky) water), Backcountry series (1-2 persons, suitable for clear or slightly turbid water), and the Ultralight Series product described above, intended for single person use and a clear water source outdoors or while traveling and staying at hotels that may provide a questionable water supply. The Miniworks® EX Microfilter water filter and pump system produced by MSR (Cascade Designs, Inc.) a camping equipment manufacturer, is built around a field-maintainable ceramic filter element that can be washed in the field for full filter recovery. [See our comments about larger ceramic water filters, below.] The filter system includes a block of activated charcoal to assist in removing water odors and some chemicals (and thus water taste). Plastic tubing (a hose float), scrubbing pad, and storage sack are provided by the producer. Like Katadyn, MSR produces several product ranges of water purification systems including their Expedition water treatment system (MIOX® purifier, municipal-grade water purification, no pumping, maintenance, or iodine; MiniWorks EX microfilter [discussed above], field maintainable, carbon/ceramic filter element that can be field-renewed), their Fast & Light water treatment system, and their Basecamp water treatment system.
The photo at left (courtesy Katadyn) shows a replacement ceramic filter element for a Katadyn Pocket filter system. In the event that the municipal water supply system is working after a hurricane, flood, or other disaster, companies like Katadyn also produce water filters that can be attached to a faucet and are operated by system water pressure. Doulton® is a company in the U.K. with branches in the U.S. that produces a wide range of ceramic water filtration equipment including point of use filters (POU filters) and filters that can operate by gravity rather than requiring a pump. A gravity operated ceramic water filter would be an effective means of sanitizing water from a rooftop water cistern. Small portable water filters are produced by Pure Water 2Go®, and MSR MiniWorks® Water Filter. Small and larger capacity portable ceramic water filters are available from many sources including camping equipment suppliers and water treatment equipment suppliers such as Crystal Clear Supply. Charcoal Filters for Water PurificationCharcoal water filters are often used as a step in water treatment systems, combined with a chlorination system. A standalone charcoal filter for portable temporary water purification risks becoming contaminated with bacteria. See WATER FILTERS for details of that device. Magnetic Water Purifiers?Magnetic water filters and purifiers: are junk science and are not a reliable means of assuring safe drinking water. Paper or Polypropylene Water Filter Cartridges - Emergency Use SuggestionsPaper or Polypropylene Cartridge type water filters (shown at page top): Our page top photo of Sears Kenmore® water filter cartridges shows how not to try to "purify" drinking water. This propylene filter cartridge is designed for use in a residential water filter canister to remove sediment, silt, rust, or iron particles - see WATER FILTERS for details of that device. In fact, Sears® includes a notice on the package "Warning: do not use [cartridge water filters of this type] where water is microbiologically unsafe or with water of unknown quality". Paper, charcoal, or other water filter cartridges can be used in an emergency, however, to pre-filter water that is to be further treated with a disinfectant. If the emergency water supply is cloudy, visibly muddy or dirty with sediment, filtering the water through any filter that happens to be on hand will reduce the debris in the water and improve the ability of the next water disinfection step to operate more quickly and reliably. Beginning at DRINKING WATER - EMERGENCY PURIFICATION we list various water disinfection and treatment options. Portable Bag-Type Filter-Based Water Purifiers
Reverse Osmosis for Water Purification in an EmergencyReverse osmosis also removes most contaminants from water; however in an emergency where public water supplies and/or electrical power are not provided, we do not assume that a home or building reverse osmosis system will be functional. If, however, the building has water pressure, a RO system will work just fine since normally these systems use only water pressure to operate the filter system. Locate the RO system in the building and follow the water piping leaving that device so that you are sure to take drinking water only from fixtures that are supplied with treated water. Even in this case, if the building water piping downstream from the RO system has been flooded it will be unsanitary and is likely to need disinfection before water taken through that piping can safely be consumed. See REVERSE OSMOSIS WATER TREATMENT for photographs of what RO equipment looks like and other details about that water treatment method. Portable reverse osmosis water treatment equipment is available from companies such as Crystal Clear Supply. Silver Ceramic Water PurifiersSilver ceramic water filters are ceramic water filters which have been treated with colloidal silver - a step which increases filter effectiveness by killing bacteria in water passing through the system. Sink Cartridge Type Water Filters as Water Purifiers in an EmergencySink cartridge water filters: We would not rely on the smaller store-bought filter cartridges that are simply attached to the tip of a kitchen sink faucet without clear documentation about just what that filter cartridge can remove from water, and how many of gallons of water it can process before it is exhausted. It would be unsafe to continue to "purify" water through an exhausted cartridge like filter. In contrast, ceramic water filters have a very high gallon capacity and most models can simply be cleaned and re-used. Guide to UV Lights for Emergency Water PurificationPortable UV Light Sterilizers for Emergency Drinking Water - the SteriPen®
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. 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:
As we discuss in more detail at UV -ULTRAVIOLET LIGHT 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. 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. -- [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. 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
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: OPINIONL: 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 see UV -ULTRAVIOLET LIGHT TREATMENT for details of residential type UV light water treatment systems as well as a discussion of when such systems are useful and appropriate. 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 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. Frequently Asked Questions (FAQs)... Ask a Question or Search InspectApediaUse the search box below to ask a question or to search the InspectApedia.com website. Ask a Question or Enter Search Terms in the InspectApedia search box just below. Technical Reviewers & ReferencesRelated Topics, found near the top of this page suggest articles closely related to this one.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
| ||||||||||
The best procedure if you don't know much about the water condition is to filter it before and after it is treated with bleach, chlorine, iodine, or other sterilization methods. 
Other, heavier, larger ceramic water filter systems such as a model we used during weeks of rafting down the Colorado River, are intended to deliver a larger quantity of potable water: these models can be inserted into a larger container of water. The hand pump draws water out of the container, through the filter, and then delivers it out of a spout or tube into a clean container for drinking or other uses.
The Home Reference Book - the Encyclopedia of Homes
