Q. The duration of contact of chlorine with water before it is served to the first consumer, shouldbe at least (Solved)
1. 10 to 15 minutes
2. 15 to 20 minutes
3. 20 to 30 minutes
4. 30 to 40 minutes
- c. 20 to 30 minutes
1. 10 to 15 minutes
2. 15 to 20 minutes
3. 20 to 30 minutes
4. 30 to 40 minutes