Public water supplies maintain a residual chlorine concentration for pathogen protection of roughly______________?
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Answer: B. 0.05 to 0.5 ppm
Explanation
To ensure continuous disinfection without health issues public water supplies maintain residual chlorine between limits. A residual concentration ranging from zero point zero five to zero point five ppm protects against contamination. Maintaining this specific residual level prevents bacterial regrowth throughout extended municipal pipe distribution networks. Chlorine residual acts as a chemical barrier protecting treated drinking water from secondary microbial contamination. Excessive chlorine concentrations produce unpleasant tastes and odors causing consumer complaints in the community. Water utilities measure free and combined chlorine residuals daily at various points across the distribution grid.
Zero point zero one to zero point zero five ppm is too low to provide reliable pathogen protection. Zero point five to one point zero ppm is sometimes used for breakpoint chlorination rather than standard maintenance. One point zero to five point zero ppm exceeds normal drinking water standards and causes strong chemical odors.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
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