By Mark Geisberg, Ph.D.
Summary: Perhaps nothing has stood out in quite such contrast over the past five years in terms of technological advancements in the water treatment field as the ability to detect contaminants much more quickly, accurately and cost-effectively at more minute levels than possible before. The following is a discussion of that.
Contamination of drinking water remains one of the most commonly cited health concerns by consumers across the United States and in other countries. In recent years, highly publicized incidents of water contamination by chemicals, bacteria and parasites have added to the public awareness of the importance of maintaining a safe drinking water supply. A large and evolving home water treatment industry has grown in response to consumers’ need to ensure safe levels of many possible contaminants.
But how can consumers determine what treatment options are appropriate for them? And how can dealers and small water systems assure their customers the water treatment devices used on their drinking water are actually doing the job? The answer lies in diagnostic testing of drinking water supplies before and after treatment.
The problem
Biological and chemical contaminants (see Table 1) can enter the water supply from many sources and pose a variety of risks to human health, water quality and the integrity of the water delivery system. Contaminants can enter the water supply before the consumer has any control over contamination levels. For example, pesticides, nitrates and nitrites come from agricultural runoff, while iron and hardness are mainly a function of the local water source. Bacteria and parasites can pose problems at various points in the water supply system, affecting whole communities or individual homes. Other potentially toxic substances, such as lead, copper and chlorine, can come from within the home or from treatment and disinfection of water. Pesticides, nitrates, nitrites and lead are serious health hazards—and their presence may not change the smell, color or taste of the water. Iron, hardness and chlorine mainly affect aesthetic qualities of drinking water and can also drive up costs of water system maintenance. Regardless of the contaminants’ source, customers need to know what’s present in their water and be certain contamination is removed before water comes out of their faucet.
The challenge for homeowners, small water systems and the dealers that service them is to maintain control over a wide range of possible contaminants through constantly changing contaminant profiles—and to do this within a small customer’s budget. There are many treatment options available for in-home and system-wide use. The water treatment professional must analyze risks present in a particular water system and provide an effective and affordable treatment. Moreover, the consumer should receive follow-up assurance that the treatment is successful in removing the unseen contaminants on an ongoing basis.
Cost prohibitive no more
Until recently, the cost of water testing has precluded routine monitoring of water in small systems and individual homes. Even large community water systems had to be selective in their testing schedules and choice of monitored contaminants. After all, a single pesticide screen by standard methods can cost hundreds of dollars. In addition, results of tests were often unavailable for days or weeks. Thus, onsite testing was uncommon.
Today, new technological advances have resulted in the transformation of many laboratory tests into quick, low-cost and disposable testing methods that allow onsite testing and frequent monitoring of many contaminants. Using these cost-effective tests, dealers, small systems and even homeowners can conduct their own comprehensive testing to ensure that their drinking water complies with U.S. Environmental Protection Agency (USEPA) safety standards for many contaminants. These can be found at the USEPA webpage: http://www.epa.gov/safewater/standards.html.
Testing options
Previously, tests for most contaminants listed in the above website and Table 1 had to be performed in a laboratory by trained technicians. Lab testing methods are still the most precise and sensitive, but they’re not practical for onsite testing or frequent monitoring. In the last few years, onsite test kits have been developed for a wide range of contaminants.
Test strips
Many are simple strips that inform the user of the level of contaminant by a color change, easily read by eye. (NOTE: foto here.)
The key features of these tests are
- Quick results: Most kits provide results within minutes.
- Simple procedure: No measurement, no equipment required, usually a one-step procedure.
- Ruggedness: Use anywhere, on water that requires no special treatment.
- Accuracy: Many tests are calibrated to the USEPA maximum contaminant level (MCL) or other safety levels for each contaminant.
- Low cost: Most tests cost less than $5 (and bulk purchasing can further reduce the cost).
While litmus paper and other pH strips have been available for many years, the range of similar strip-type tests has expanded to include chlorine, iron, copper, nitrates, nitrites, hardness and other contaminants. These tests—aimed at contaminants with safe levels above 1 part per million (ppm)—utilize chemical reactions to produce color changes that give the result.
Immunoassays
Now, a new generation of tests, based on biochemical reagents called antibodies, has enabled rapid tests to reach sensitivity levels 1,000-fold lower, to less than 1 ppb. These tests, called immunoassays, can accurately detect the most toxic chemical contaminants, such as pesticides and lead, at their MCL (see Table 1). For example, a one-step immunoassay test for lead scheduled for release this summer is designed to replace and improve upon the current cumbersome lead test for detection to these levels, which involves concentration, measurement and reaction steps. (NOTE: foto here)
Tests for bacteria and parasites have been notoriously difficult to transfer to onsite use. Currently, testing for bacteria involves concentration and culture steps that are laborious and time-consuming, making frequent testing unattractive to most homeowners and small systems. In the near future, however, rapid bacterial tests based on immunoassay technology also are scheduled to be introduced that will target coliform bacteria as an overall indicator of microbiological water quality, as outlined in USEPA and American Water Works Association (AWWA) standards. The major advantage of these new tests will be elimination of the time-consuming culture step that’s required in current bacteria tests, even those with “rapid” or “quick” in their names.1 And, unlike culture tests, the immunoassay method is not prone to false results due to light sensitivity, medium sensitivity, and other problems. The introduction of one-step immunoassay tests for bacteria will allow truly convenient water system monitoring by individual homeowners as well as larger water systems.
Conclusion
Recent advances in testing technology have brought accurate, cost-effective detection of drinking water contamination within reach of homeowners and small water systems. These tests cover a wide range of contaminants and give results within minutes. A monitoring program that uses rapid, onsite tests can build customer trust and loyalty by assuring consumers that their water treatment systems are providing effective protection for their home and health.
References
- Haubrich, M., “Coliforms and E.Coli Detection Made Easy,” WC&P, August 1999, p. 48.
- Consumer water treatment guide is available at: www.wqa.org/Consumer/water_treatment.html
About the author
Dr. Mark Geisberg is the research and development director at Silver Lake Research Corporation of Monrovia, Calif. Silver Lake Research develops and markets biotechnology-based rapid tests for a variety of drinking water contaminants, including unique, one-step immunoassays for pesticides, lead and bacteria. He can be reached at (888) 438-1942 or (626) 359-8441, (626) 359-6601 (fax), email: [email protected] or website: http://www.silverlakeresearch.com