Originally Posted By red_on_black:
I have more commonly seen 8 drops per gallon. Also, 1 U.S. gallon = ~3.8 L and that table uses units of Imperial gallons, which most Americans will be unfamiliar with. Neither makes very much difference:
0.18mL/4.5k mL x 60 ppt = ~2.4 ppm
0.72mL/3.8k mL x 60 ppt = ~11 ppm
This is still on the order of about 10 times the normal amount of chlorine found in chlorinated drinking water (0.1-1 ppm). As others have already said, if you're storing clean tap water in clean containers no additional chlorine is necessary.
Good catch. I was looking for a table I could copy and paste quickly and didn't catch the Imperial gallon distinction.