Enhancing water quality surveillance: a comparative analysis of water testing Portable Microbiological Lab and the colilert Quanti-Tray 2000

Abstract

Background : Operational water quality surveillance dominates urban piped systems. Lack of it poses a serious risk to public health as the population is exposed to disease causing microorganisms; responsible for between four and six million cases of diarrhoea and more than 1,300 fatalities each day. Thus a need to determine the accuracy and reliability of the Portable Microbiology Lab (PML) for point sources of water, both protected and unpro tected.

Metholdology : The study evaluated the field test method, PML Kit under different water source conditions by comparing it to a laboratory standard method Quanti Tray. This was executed by analyzing 27 water samples.

Results : PML and Quanti Tray 2000 yielded matching risk level results for 26 samples. For the qualitative test of the 10mL and 100mL Colilert; 4 of the 27 samples' presence/absence tests were not congruent with each other. Thus error for a test with 10mL Colilert of PML
resulted in a percentage variation of 14.81%, a sensitivity of 82.6% and a specificity of 100%. The addition of Petrifilm to identify risk levels, the proportional reduction in error relative to water source designation, for improved water source; for moderate levels at 30.78%, low risk 30.78%, high/very high risk was at 7.69% with a statistically significant differenceχ 2 (2, n =13) = 30.78, d.f. =2, (p <0.0001).

Conclusion : The Portable Microbiology Laboratory offers accurate and reliable water quality assessment in line with the WHO disease risk levels and serves as a basis for informed management and public health interventions.