PORTABLE WATER TREATMENT PRODUCTS
Options in Application and Technology
The range of portable water treatment products has expanded significantly over the last several years. Much of this expansion is due to the increased variety of technologies and media available in the market. These technologies have enabled manufactures to produce products with greater reduction capabilities.
Although new technologies and media have enabled manufacturers to improve product performance there has been little change in either the types of products or the basic applications. Water bottles, gravity feed/pour through devices and hand held pump/filter units continue to be used to replace bottled water, during outdoor recreational activities and travel and for emergency preparedness. In addition, sometimes 'questionable' quality of bottled water and concerns about chemicals leached from plastic containers has further increased the demand for this type of product.
PORTABLE WATER FILTRATION TECHNOLOGIES
There are multiple technologies and media currently used in portable water treatment devices, some are common and some are new. Each is used to address a specific contaminant or water problem. In many cases several of these technologies are used in conjunction with one another to create the end product.
Spun Polypropylene is used as a filter to reduce sediment, dirt and turbidity that may be present in the water source. It is also useful as a pre-filter to protect a secondary stage of treatment such as ceramic filters, porous molded plastic, carbon block and/or membrane.
Porous Plastic technology can be applied in a variety of ways, contingent upon the finished products micron rating; to reduce sediment, as a spacer between media layers, or as a method of mechanically reducing cysts and bacteria. (I've explained micron rating in my article...we may have to mix and match a bit.)
Granular Activated Carbon is used to improve taste and odor by reducing chlorine, industrial chemicals and a multitude of organic contaminants. Additives to GAC may help to reduce lead, some forms of heavy metals and additional contaminants. GAC can also be used as Pre and Post Filtration for other technologies and as a method for removing chlorine or iodine after disinfection.
Carbon Blocks perform the same function as GAC. In addition, based upon micron rating, carbon blocks have cyst and bacteria removal capabilities via mechanical filtration.
Ceramics will mechanically filter waterborne pathogens such as cysts and bacteria. Their effectiveness in a given application is dependent upon choosing the right micron rating for the application. Various micron ratings are available.
KDF is generally used to compliment other methods of treatment. It has a high capacity to remove chlorine and selectivity for such contaminants as lead, arsenic, cadmium, mercury, calcium carbonate and magnesium. In addition it is bacteriostatic.
Membranes are in use or are being evaluated for use in portable devices. Their sub-micron pore sizes enable them to eliminate cysts, bacteria and in some cases viruses. Sediment pre-filtration is necessary to protect the small pores from clogging.
Iodinated Resin has proven to be an excellent method of eliminating bacteria and virus from raw water. Though effective, these resins have specific operating parameters. Use outside of these parameters will negatively impact the products effectiveness. A post media is used in conjunction with iodinated resin to eliminate the concern of iodine or iodide in the product water.
Ion Exchange Resins are used to remove selected contaminants. Resins are manufactured with this selectivity in mind. For example, a specific ion exchange resin is produced to remove nitrates.
PORTABLE WATER DEVICES
Pour Through/Gravity Feed Units
These units vary widely in size. One of the smaller units is an 8 oz. inverted cup using carbon to improve taste and odor. This unit has a 50 gallon capacity. An example of the larger unit would be a terra cotta or stainless counter top unit using ceramics with media capable of reducing a multitude of contaminants including cysts, bacteria, lead, chlorine and other heavy metals. The most versatile, durable and portable of these large units is the Outback. This system breaks down for storage and travel. It uses filters and chloro tabs to remove bacteria, cysts, virus, chlorine and organic matter. The large units have a 2,500 gallon capacity and replaceable components. Many of the higher end products have been tested to ANSI/NSF Standard 53 by credible independent laboratories.
There are several portable bottle units on the market. There is a broad range of performance and price - the higher price not necessarily indicative of higher levels of performance. Some bottles do their job using a single filter. To achieve the same result others require that the filtration component be changed once or even twice during a single use. The most common performance claims are those of improved taste and odor. This is achieved using a simple carbon filter that fits inside the bottle. Other bottles are capable of bacteria and cyst removal/reduction through the use of carbon blocks, porous molded plastic or ceramics. Finally, in some cases the bottles can reduce viruses through the use of membrane and/or iodinated resin. There are several bottles that offer replaceable filters while others have filters permanently affixed to the unit, a straw or to the filter cap. One product actually opens from the bottom of the bottle, allowing it to be used as a bottle and as a pour through/gravity feed unit in conjunction with a larger container. Again, third party testing is a critical consideration when evaluating these products.
Pumps and pump/filter combinations usually use a technology such as Carbon blocks, ceramics, porous plastic elements or membranes to effectively remove protozoan cysts and bacteria. It is generally a good idea to incorporate some type of pre-filter to eliminate particulate that are larger than the pore size that could cause premature clogging of the filter. These products are used primarily in the outdoor specialty markets. Because this application may entail challenging a product with high levels of contaminants in 'worst case conditions' the issue of performance testing becomes very important.
Many of the available portable products can be used in a multitude of applications. Within each product type are individual products that are capable of producing potable water from non-potable raw water sources, either by significantly reducing bacteria or cysts or sediment etc. They can also be used in non-traditional ways, both inside and outside the home and in emergency or survival situations. A sports bottle can be used to replace bottled water while at school, while traveling or during any recreational activity. Some are designed specifically to filter water for babies while others can double as gravity feed treatment/filtration devices to fill larger water containers. Some have capacities of as little as 25 gallons and some have capacities as high as 200 gallons. Some remove only chlorine while some have proven effective against bacteria, cysts and virus. Countertop gravity flow devices can replace bottled water without the connection to the faucet. They can treat, filter and cool the water and are easily emptied and moved. There are those that have the same range of performance characteristics as sports bottles. Although their applications differ due to their size their capacity is higher than that of a sports bottle. Combination pump/filter units are useful in both outdoor and emergency situation where the user might need to capture water from streams, rivers, lakes, or other suspect water sources.
Though virtually all of the technologies used in portable filtration devices are also used in larger (Counter top or Whole House) systems the amounts of media used are significantly smaller, hence the portable systems generally have a much lower performance capacity. Many of the devices using mechanical filtration have capacities similar to their larger counterparts. In the event that the product is to be used as a water purifier and listed as such, the product must pass the stringent performance evaluation required by the EPA. For all of these reasons it is critical to ensure that portable units have been sufficiently tested and evaluated by an independent third-party laboratory and that the test results support any claims made by the manufacturer and are available for general distribution to the buyer.
WHAT PORTABLE PRODUCT DO I CHOOSE?
Use the following process to weed out the good from the not so good.
What contaminant do you want to remove? What are the problems in water supply in question (chlorine, lead, cysts, bacteria)?
Identify media or technology:
What technology is necessary to improve aesthetics and/or remove contaminants.
Which type of product (or combination of products) will produce the water you need (bottle, gravity feed system, etc). Once this is decided focus on products using this technology or media combination and making claims to remove the contaminants you have identified.
Verify application given its operating parameters:
Make sure the product will work properly in the environment where you will use it. For example, a water bottle using iodine to remove bacteria will not be effective when used in freezing temperatures by cross country or downhill skiers. It only 'works' within a certain range of temperatures. Products may be rendered less effective by a variety of conditions. These should be clearly stated in the operating parameters furnished by the seller.
Verify the veracity of claims:
Ask the seller or the manufacturer to send you copies of third party tests done by reputable labs showing the product can and has performed in accordance with claims.
Evaluate ease of use:
Will product meet claims and be easy to use in the environment of its intended use (outdoors, in an emergency situation, etc.)
Evaluate capacity in terms of need:
Will the product produce enough potable water to meet the your needs in its intended application
Evaluate value versus price:
Don't assume that the higher price buys a 'better' product. Competing products often use identical technology and differences in price can be the result of fancy packaging or presentation.