Make sure you let it sit for 30 minutes after adding the bleach before you drink it, preferably longer. The longer it sits, the lower the bleach concentration will be, but the first 30 minutes are to let it do its disinfecting work.
Offered by Toni.
Chlorine is a gas in its natural state. Chlorine tablets will dissolve the chlorine in water, but the chlorine will eventually evaporate from the water, especially in the sun as any pool owner can tell you. I'm not sure of the rate at which evaporation occurs, but the drops to test chlorine in water can be purchased at any pool supply place for just a couple of dollars.
Offered by Steve.