4. Steele, M., A. Mahdi, and J. Odumeru. 2005. Microbial assessment of irrigation water used for production of fruit and vegetables in Ontario , Canada . Journal of Food Protection 68: 1388-1392.
A total of 501 farm irrigation water samples were collected and analyzed for presence and numbers of various bacterial water quality indicators. The majority of the water sources were holding ponds on farms and water flowing naturally into these holding ponds. The farms in the study had little or no livestock production. Most of the samples tested were acceptable in terms of the fecal indicator bacterial groups fecal coliforms, E. coli , and fecal streptococci. However, many samples exceeded recommended levels for total coliform bacteria (which can be from fecal or non-fecal sources). Of these latter samples, 45% could be considered unacceptable for irrigation of crops to be consumed raw. Higher bacterial levels were associated with recent rainfall, although warmer weather and decreased water levels in ponds may also cause an increase in bacterial levels. The authors suggest that water used to irrigate crops that will be consumed without cooking should be tested regularly to ensure that it is of acceptable quality. Testing for one type of indicator bacteria, such as E. coli , should be sufficient, as the results for the different types of tests were closely correlated.
Key words: microbiology of water
