Our evaluation of home water treatment devices began with an examination of distillers. All three of the units that we discussed qualified as water purifiers (that is, the devices removed or killed all bacterial impurities), yet they crossed an impressively broad range of capability and cost. Similarly, the pieces of filtration equipment we're reviewing in this installment vary considerably in both capacity and price.
However, the seven filters we've had a chance to appraise do have one thing in common: They all employ activated carbon to filter out chemical impurities such as carcinogenic trihalomethanes. (Note: Although they, too, use charcoal, the General Ecology units rely on an even more effective microstraining system for their primary impurity removal.) Activated carbon — which is also called charcoal — has been used for cleansing for over 100 years . . . functioning, for example, as the stripping agent in World War I gas masks and as the medium used for decolorizing sugar. It's only recently, however, that the versatile material has come to be used in water filtration.
Because activated carbon's "cleaning" ability depends entirely on the amount of surface area contact between the cleanser and the water that's available, a filter's performance is largely determined by the volume of carbon inside it and the length of time the water remains in contact with the carbon ... a consideration which is called "residence time." Unfortunately, extensive residence time can result in the growth of bacteria on the charcoal . . . and each of the manufacturers included in our study has dealt with that problem in a different fashion.
American Water Purification
Both of the California-based American Water Purification Company's filters have silver infused into their charcoal to inhibit any bacterial growth. In addition, the smaller of the two units — the Water Washer — has built-in flow control to prevent the operator from inadvertently reducing residence time below a safe level. Another useful feature of the limited-capacity model is a viewing port to give the owner a visual warning when the filter element is dirty.
The UTS Silverator is an under-sink model which can be used either to filter all the cold water at that location, or to deliver the cleansed liquid to its own faucet to be used for drinking and cooking only. In the latter application, the Silverator's 5,000-gallon-life filter should last for a very long time.
The Louisville, Kentucky manufacturer's product is by far the most ambitious filtration setup of those we sampled. Its capacity as well as its size is several times that of any of the other devices . . . great enough, in fact, to process all the water entering a household. Furthermore, even at its maximum flow rate of two gallons per minute, the BestWater retains water for a full two minutes and provides about one year of filter life. Since the unit is almost constantly in use on a residence's main water line, bacterial build-up isn't a problem.
Both of this company's Seagull models are unique among water filters because they are classed as "purifiers" by the Environmental Protection Agency. The devices remove bacteria — as well as cysts, amoebae, protozoa, and small fragments of materials like asbestos — by a microstraining process which is effective down to 0.4 microns. (For comparison, a red blood cell is about 7 microns.)
The Seagull 1.5L is a limited-capacity unit designed primarily to purify drinking water. It is available with a hand pump for remote use, and the filter element is actually the body of the device. The larger model, the Seagull IV, can be used under a sink or on the countertop. With 1,000 gallons (approximately) of useful filter life, the mid-sized "strainer" can be expected to treat all the water used in a kitchen.
Sears, Roebuck and Company
In the manuals for the two Sears water filters we sampled, the firm recommends that if either unit has been unused for over a day the element be flushed with a brief flow of water before use . . . thereby extracting any bacterial growth. The technique is effective but, of course, does waste a portion of the filter's treatment capacity.
The Instapure by Water Pik is the smallest filter we examined. It attaches to the end of a faucet and is designed to be used at less than 1/2 GPM ... although, because of the device's limited area of filtration, we'd be inclined to keep the flow rate to about a quart a minute.
On the other hand, the Taste and Odor filter is a large-capacity unit which — like the UTS Silverator — can be used either to treat all the water at one sink or to deliver cleansed liquid to a specific separate tap.
In addition to its line of filters, Sears offers a free water evaluation service — available by mail or through any catalog store — which provides an analysis of your water quality and offers suggestions for treatment techniques.
How Far Is Up?
Choosing a filtration system for your home depends for the most part upon what kind of treatment you need and how much liquid you will want filtered. Units as large as the BestWater can help eliminate ugly rings in your bathtub as well as provide high-quality drinking water. But if you're looking only for something to give you a better glass of water than you normally get from the tap, the Instapure will do the job.
Of course, General Ecology's devices — because they're officially classed as purifiers — can be expected to provide exceptionally high-quality liquid . . . and will even render unsafe water potable. And the American Water Purification filters offer a viable mid-capacity, mid-price solution to extracting nasty chemicals from your drinking supply.
Each of the filters that we've examined proved to be a well-put-together piece of equipment designed for a particular purpose. Once you've determined what your needs are — perhaps by having a water sample analyzed by Sears or another laboratory — you can pick any one of them with confidence.