The presence of the bacterium Escherichia coli indicates recent fecal contamination of water.
First step: gas from lactose broth at 35°C.
2nd step: 2nd lactose broth incubated at 44.5°C +/- 0.2°C. Gas produced by 'thermotolerant coliforms'
Most strains of E. coli produce gas at 44.5°C
But so do environmental coliform bacteria like this Klebsiella sp. The thermotolerant coliform test is not specific for E. coli.
The burden of collecting and using firewood to cook food for ~2.5 billion people in developing countries
Tree cutting leads to deforestation and land degradation
Barbara Kerr and Sherry Cole developed a practical solar box cooker in 1976.
Regular solar cooking in Sacramento since 1978.
Solar cooking in Sacramento, California, June, 1991
Bolivia, 1987, teaching how to build and use a solar box cooker. No simple water test available.
Guatemala, January, 1998.
Built solar box cookers but no simple water test available.
In 1988, a new approach to test for E. coli is announced. Colilert, a defined substrate test
Colilert was available as a dry powder in glass tubes to test 10 ml of water. Made by Access Medical Systems, CT.
IDEXX took over production of Colilert from ACCESS in 1993.
January, 1989, Sierra Leone. With Colilert, water testing could be included with building solar box cookers.
First solar box cooker made in Sierra Leone
Cake baked in solar box cooker for 2 hours
Fish soup & rice solar cooked
Distribution of Colilert tubes to 41 workshop participants to sample home water source.
Tubes can be incubated next to one's body to obtain next day results.
Body incubation of Colilert tubes
Next day results.
Clear = no coliform bacteria. Yellow (ONPG+) = coliform bacteria present, possibly E. coli
Shine a long-wavelenth UV light on tubes. Blue fluorescence = MUG (+), E. coli is present (right tube). MUG (-), E. coli not present.
39 of 41 tubes were ONPG + (yellow), coliform bacteria present, perhaps E. coli.
26 of 41 samples were MUG (+), indicating the presence of E. coli.
Bamako, Mali, 1991. 33 water samples, 19 ONPG (+), 12 MUG (+).
Noukchott, Mauritania, 1991. 24 urban water samples were inoculated into Colilert tubes
Solar box cooker made at workshop.
Of 24 urban samples, 20 were ONPG (+), 12 were MUG (+)
Nepal, 1993. Colilert results from this source were ONPG (+), MUG (-).
Solar box cookers in Nepal, 1993.
Colilert results, urban and rural water sources tested
22 total sources tested. 21 ONPG (+), 9 MUG (+)
Somali women returning from 8 hour journey to collect wood, Dadaab refugee camp, Kenya, 1995
Refugee children returning with sticks after a long journey.
Introduction of the simple Cookit solar cooker. Foods cooked inside clear plastic bags.
Cookit among refugee dwellings.
Refugee family with Cookit.
Solar cooking works!
Testing borehole water with Colilert. ONPG (+), MUG (-)
In 1995, E. coli Count Petrifilms were available to test 1 ml.
To use Petrifilm, label sample source and time
Add 1 ml of water sample to nutrient circle
Use flat side of plastic spreader to gently distribute 1 ml over entire circle
Petriflms covered with firm cardboard enables incubation on one's body. Invisible bacteria to develop into visible colonies in 12-16 hours.
Results usually in 12-18 hr. E. coli = blue colonies with gas. Coliforms from environment = red with gas.
First use of E. coli Count Petrifilm on raw camel milk in Dadaab refugee camp
Inoculated Petrifilms with 1 ml. Incubated on body between cardboard pieces to obtain overnight results.
Next day results. > 200 E. coli/ml before pasteurization.
Colilert and Petrifilm tests correlate with risk of disease, WHO Guidelines for Drinking Water Quality, 2nd Edition.
Colilert and Petrifilm results also correlate with MSF treatment guidelines in emergencies.
Students at California State University, Sacramento, who contributed to water pasteurization work
Heating water to 65°C will pasteurize water and make it safe to drink.
Water Pasteurization Indicator (WAPI). When water reaches 65°C (149°F), wax melts and falls to the bottom. Water is pasteurized.
Article on Cookit and WAPI to pasteurize water, 1999
Water Pasteurization Indicator used by Dadaab refugees who received Cookit solar cookers.
Fuelwood problems in Meatu District, Tanzania, 2000
Water source, Meatu District, Tanzania
Sampling water source, Meatu District
Removing water sample for Colilert and Petrifilm tests, Meatu District
Water source, Meatu District
Water seller collecting water in Meatu District
Components of the Portable Microbiology Laboratory to test water in Meatu District
Materials for 25 water tests in gallon-sized plastic bag to make a Portable Microbiology Laboratory.
Any table becomes a laboratory to test village water sources
Testing numerous water sources in Meatu District
Results from one village. 1 ml removed from Colilert tube for separate incubation.
Results of Meatu water tests.
Demystifying microbiology, teaching community about bacteria and water testing
Topics covered include bacteria size, growth, E. coli as indicator, Colilert & Petrifilm tests, WHO disease risk guidelines
Village chiefs and village health workers in 3 day workshop.
Next day results. Most local water sources from dry riverbed were high/very high risk.
Village chief knows that MUG+ Colilert means that E. coli was in the town's river water source, unsafe water
Health worker finds >10 E. coli on Petrifilm, a very high risk of disease
Water testing workshop for Saka Saka village. Boniphace will translate into Kiswahili.
Two water sources in Saka Saka. From a pump (green bucket) and an open stream (yellow bucket).
Adults will sample either pump or stream water
Mixing inoculated Colilert tubes, to incubate overnight
Next morning demonstration of solar cooking, solar water pasteurization
Read results: Pump water yellow, MUG -, no E. coli. Stream yellow and MUG+, E. coli present.
Petrifilm results are clear.
Stream water (front) with ~100 E. coli colonies on each Petrifilm, very high disease risk. Pump water (back) with environmental coliforms,no E. coli, low disease risk.
All villagers see results of grossly contaminated stream water, no E. coli contamination of pump water.
Solar cooked rice in 2 hr
Providing a year's supply of water testing materials to Saka Saka health workers to monitor pump water
After only an afternoon and a morning session, Saka Saka village understands the microbiology of water testing.
Competence in water microbiology is established in the village.
Guest House (hotel) in Meatu District
River water provided for guests
After testing river water, collect for solar pasteurization
Heating river water in Cookit to pasteurize
Temperature >60°C in 2 hours
WAPI wax melted, water is pasteurized
Evidence-based microbiology that contaminated water has been pasteurized.
Poster at 2001 American Society for Microbiology Annual Meeting
Poster at 2003 American Society for Microbiology Annual Meeting
Poster at 2005 American Society for Microbiology Annual Meeting
Water testing booklet published by UN-Habitat, 2010.