Liquid bleach is not very stable and breaks down gradually over a period of time. It is still usable after about 6 months but you will have to use more than you normally would to achieve the same results. This will lead to a very rapid decrease in your ability to treat your water sources in order to make them safe to drink. Calcium hypochlorite, better known as pool shock, will keep in its dry form for approximately 10 years. Liquid chlorine bleach will lose most of it's potency after only a year and will eventually degrade (turning into salt water) until it is useless as a chemical treatment for your water.
Dry granules of calcium hypochlorite (pool shock) can be used to make your own liquid bleach as it is needed and allow you to have a reliable source of fresh bleach for water treatment purposes. Calcium hypochlorite is very inexpensive and can be purchased anywhere swimming pool supplies are sold. You will need to obtain the plain variety which does not contain any algaecides or fungicides. You will also need to store it in an airtight container in a cool, dry place. Remember it must be 65% calcium hypochlorite only with no additional anti-fungals or algaecides. Calcium hypochlorite granules are highly corrosive and should be stored in an air-tight, plastic container for best long term storage results. Using liquid bleach is an excellent short term water purification solution, while dry granular bleach is much better for long term water purification needs.
Here is a link to a resource for calcium hypochlorite:
Calcium Hypochlorite granular Ca(OCl)2 68%CL2 2 lb bag (Free Shipping)
You can also get additional information about water treatment here: Water Treatment and Storage .
It is important to remember that, prior to chemically treating your water, it may also need to be filtered to remove other contaminants. This will require the use of an improvised filter (bandana, coffee filter, etc.) or commercially available water filters such as the Berkley or Katadyn brands.
Note: Always practice water conservation. The water you conserve could quite possibly safe your life in an emergency! To put
this into perspective, people who consider themselves a partsgeek would work with cheap auto parts and would be versed with the ins and outs
of automotive parts just as someone who is a prepper should be doing everything
they can to be as prepared as possible in a survival situation.
You can check out my article for some helpful tips here: Preppin' 101 - Part 2 - Water Conservation.
Staying above the water line!