Minimum chlorine content of water after effective chlorination should be of which of the following concentration given below?
The minimum recommended concentration of free chlorine is 0.5 mg/L for one hour. The free residual chlorine provides a margin of safety against subsequent microbial contamination such as may occur during storage and distribution. The sum of the chlorine demand of the specific water plus the free residual chlorine of 0.5 mg/L constitutes the correct dose of chlorine to be applied.
0.5 mg/L
5 mg/L
0.05 mg/L
50 mg/L