| 101 Technologies - From the South for the South |
In Malaysia, as in many other countries, testing the quality of drinking water is essential to protect people from water-borne diseases such as cholera, typhoid fever, dysentery, polio, and hepatitis. Standard methods to test bacteriological water quality are costly, time-consuming, and require well-trained staff and laboratory facilities. This makes it difficult to routinely test water sources in remote areas.
Researchers in Malaysia have now developed a prototype portable water-quality testing kit that is inexpensive, easy to use, and effective under field conditions. The kit uses an adapted version of a test called APHA 919C, for the detection of coliphages in water samples. Standard tests measure the presence of coliforms in the water, which is a more complex process. Coliphage testing is simpler, less expensive, and has been shown to be a useful indicator of the level of fecal contamination in the water. The test involves incubating the sample in a host culture. Various changes to the test have simplified the process and allow for incubation at ambient temperatures (25 to 35°C).
The method is useful for testing water in open wells, tube wells, rivers, and other surface waters, and small-scale water supply systems. The quality of untreated surface waters can be determined rapidly with a 6-8 hour incubation time. Standard water quality tests need a 24-hour incubation time for an accurate assessment.
The prototype kit consists of a styrofoam box in a canvas sheet, which protects the contents from sun and rain, and maintains a constant temperature inside the box. With a capacity for eight tests, each kit contains: media in bottles in stainless steel trays; the bacterial host in dried form; petri dishes; syringes; receptacles; a camping gas burner; a lighter; and a pair of tongs. It can be carried by hand, on a bicycle, or in a vehicle. It measures 38 cm x 25.5 cm x 33.5cm and weighs 6.4 kg.
The kit has proven to be reliable. The design is currently being modified for mass production. Further improvements may include: reducing the weight by using plastic bottles instead of glass; replacing syringes with pipettes; finding a less expensive gas burner. A manual and training course are also being prepared. The kit has the potential to develop self-sufficiency of communities in testing their own water.
Health and environment government departments and other organizations involved in monitoring water quality.
About half a day of training is all that is required to use the kit.
Cost and availability
The kit is still at the prototype stage. It is estimated that it will cost about US $95 for an 8-test unit, and US $175 for a 24-test unit. This amounts to US $7 per test with 44 cents per test for replacement items (media and syringes). This compares favourably with existing field kits which cost US $1000 to $1700 for a 24-test unit or about $50 to $75 per test.
Dr Wang Chee Woon Department of Microbiology, Faculty of Medicine University of Malaya Pantai Valley, 59100 Kuala Lumpur, Malaysia Tel.: 03-574 422; Telex: UNIMAL MA 39845