IWHA promotes use of the Portable Microbiology Laboratory (PML) containing two inexpensive, scientifically vetted tests, sufficient for 50 water samples. Also included are sterile collecting bags, pipettes and a battery operated UV light. All materials fit in a gallon size plastic bag and no incubator is required to obtain overnight results.
A Breakthrough in Water Testing for Developing Countries
A simple and effective water testing kit currently available that can be used at the community level in developing countries to test water sources for the potential risk of disease has been developed by Professor Bob Metcalf, California State University, Sacramento for easy use in the field. The Portable Microbiology Laboratory (PML) contains scientifically vetted tests for the fecal indicator bacterium Escherichia coli in water and food – the Colilert® 10 ml presence/absence test (IDEXX, Westbrook, ME) and the E. coli/Coliform Count PetrifilmTM (3M, St. Paul, MN), a quantitative test for 1 ml.
The PML includes 25 each of Colilert and Petrifilm tests that fit inside a gallon-size zip lock plastic bag, Whirl-Paks to collect water samples, sterile plastic pipettes, a spreader and a battery-operated long-wave UV light for the Colilert test. Just add water and incubate. All tests can be incubated at body temperature and the results obtained overnight.
The Colilert and Petrifilm tests are specific for E. coli because they contain a substrate for the beta-glucuronidase enzyme that is produced by E. coli, but not by environmental coliform bacteria. The test results are present after 12-18 hours incubation. Results provide a disease risk assessment of water sources that correlate with the World Health Organization’s Guidelines for Drinking Water Quality:
Disease
Risk Level E. coli in sample Colilert MUG+ # E. coli Colonies on Petrifilm
Low <1/10 ml – 0
Moderate 1-10/10 ml + 0
High 1-10/ml + 1-10
Very High >10/ml + >10
The PML and safe water community workshops include:
- a teaching component, easily understood by laymen, explains microbiology and the connection of contaminated water with disease.
- testing contaminated water before and after pasteurization, chlorination, bio-sand filtration, or other effective treatment process provides dramatic visual evidence of how to make water safe for drinking.
- how to introduce the PML and safe water into communities.
Use of the Colilert and Petrifilm tests at the community level in developing countries can contribute significantly to a reduction in water-borne disease.
To view photos of the PML tests and applications in Kenya and Tanzania go to:
http://imageevent.com/bobmetcalf/watertestingpasteurizationinafrica
For more information contact Professor Metcalf at: rmetcalf@waterinternational.org or Patrick Widner, Executive Director, International Water and Health Alliances at: patrick@waterinternational.org