You need to use the correct amount of chlorine. To little it does nothing, too much it's toxic and ....well there's less people who will be needing water.
http://modernsurvivalblog.com/surviv...rinking-water/
Water – Bleach Ratio For Purifying Drinking Water
1 Quart water, 2 drops bleach
1 Gallon water, 8 drops bleach
5 Gallons water, 1/2 teaspoon bleach
10 Gallons water, 1 teaspoon bleach
50 Gallons water, 5 teaspoons bleach