Pool Shock (Granular Calcium Hypochlorite) is the better long term alternative to Bleach because of it's short self life. Bleach only has a shelf life of one year and many people are surprised when they look at the expiration date on they're jug next to the washing machine and find it's out of date.
Granular Calcium Hypochlorite has an indefinite shelf life, goes along way and is easy to shore.


This came from the EPA web site.


http://www.epa.gov/OGWDW/faq/emerg.html

You can use granular calcium hypochlorite to disinfect water.
Add and dissolve one heaping teaspoon of high-test granular calcium hypochlorite (approximately ¼ ounce) for each two gallons of water, or 5 milliliters (approximately 7 grams) per 7.5 liters of water. The mixture will produce a stock chlorine solution of approximately 500 milligrams per liter, since the calcium hypochlorite has available chlorine equal to 70 percent of its weight. To disinfect water, add the chlorine solution in the ratio of one part of chlorine solution to each 100 parts of water to be treated. This is roughly equal to adding 1 pint (16 ounces) of stock chlorine to each 12.5 gallons of water or (approximately ½ liter to 50 liters of water) to be disinfected. To remove any objectionable chlorine odor, aerate the disinfected water by pouring it back and forth from one clean container to another.

As they say Prep smarter not harder.