ABSTRACT
Background: The conventional method for managing drinking water quality is not a suitable preventive strategy for protecting public health. A water safety plan [WSP] presents a systematic approach to ensuring the health and quality of drinking water. This study assessed the drinking water supply system safety of Birjand city using the WHO's WSP
Methods: This investigation employed the WSP-QA Tool and the WSP manual of the WHO and the AWI. For this purpose, software checklists were prepared and, after confirmation of content and face validity, completed based on Birjand's water and wastewater company records and interview with company's experts.Data was analyzed using WSP-QA Tool
Results: From total possible 440 points for full use of the program and 328 points of the studied phases, a score of 190 was acquired, indicating a 43.18% coordinated implementation with WSP. System description and management procedures showed the maximum and minimum percentages of congruency with the WSP of 87.5% and 25%, respectively. Among the components of the water supply system, water resource had the most attention
Conclusion: As regards the percentage of overall WSP-phase implementation and the low attention given to some key parameters of the water supply system, such as risk assessment and management procedures, the system currently enjoys a relatively medium level of safety. However, the high points of some phases such as system description, operational monitoring and verification enhance the system's flexibility for changing the current approach of qualitative management to the WSP
ABSTRACT
Legionella is one of the leading causes of nosocomial diseases. This bacterium can reproduce and survive under different temperatures, pH, nutrients and oxygen; while hot water of distribution systems provides an ideal environment for its growths. This study was carried out to identify Legionella in water distribution systems of Taleghani Hospital and to assess environmental factors affecting its growth. In this descriptive-cross sectional study which was run in summer 2011, 32 samples of cold and hot water systems of Taleghani Hospital were obtained. Samples with 1 to 1.5 liters volume were gathered and immediately concentrated using 0.45 micro membrane filter systems. BCYE culture along with GVPC, CCVC, L-Cystein and pyrophosphate Ferric supplementaries were made according to the protocol. In order to eliminate interference of other bacteia, GVPC, CCVC, and acid care for inhibition of growth were used. Then the samples were cultured and the colonies were recognized using morphology and biochemical characteristics. From 32 samples, 11 were contaminated with Legionella [34%]. The residual chlorine of samples were 0.4-1.4 [mean: 0.909 mg/L] and their pH were 4.5-8.2 [mean: 7.36]. Most of the positive cases were reported from hot water samples and also samples with residual chlorine of less than 1 mg/L. The positive samples were reported mostly from men oncology ward, storage tanks and newborn ward. Data analysis showed that there are significant correlations between legionella pneumophila growth and temperature [OR=1.676, [1.08-2.599]; p-value <0.02] and also residual chlorine [[OR= 0.006, [0.0005-0.703]; p-value <0.035]; while no correlation was seen between other variables such as turbidity and pH. In spite of the fact that the hospital uses treated water of urban distribution system, 34% of samples were contaminated with legionella pneumophila; most of them were found in samples with residual chlorine concentrations of less than 0.9 mg/L. This shows that Legionella pneumophila is resistant against antiseptic factors and hard conditions of the environment, since most of the positive cases were related to hot water samples