Chlorine bleach is a very effective sanitizer, and it has the advantage of being widely available and very inexpensive. Mixed at a ratio of one ounce per five gallons (about 1.6 ml per litre), chlorine bleach will kill even the nastiest of bugs with a 5 minute soak. Charlie Talley, a founding chemist of Five Star Chemicals, provides some great advice on using household bleach as a sanitizer. First, only use unscented, no-name brand bleach because it is unlikely to have the laundry additives that are included in the brand-name bleaches. These additives may reduce the sanitizing power of the bleach and may leave a persistent scent or off-flavour on your equipment. Second, adding a small amount of vinegar to your water will lower the pH and make the chlorine a more effective killing agent. If you follow this advice, do so with caution! The correct procedure is to add one ounce of vinegar to five gallons of water and mix it thoroughly to lower the pH of the water. Rinse any residual vinegar off your measuring spoon, then add one tablespoon of chlorine bleach to the 5 gallons of treated water and mix well. Never mix bleach and vinegar directly because it will create poisonous chlorine gas.
Bleach sometimes gets a bad name in brewing circles because if you fail to rinse it properly, chlorine residue will react with phenols in your wort to create chlorophenols, which may produce medicinal or band-aid off-flavours in your finished beer, even at very low concentrations. So two critical pieces of advice are: (1) after using bleach, rinse your equipment multiple times, and (2) dont make your bleach solution stronger than it needs to be (e.g., in many popular homebrewing books they recommend using 1 tablespoon of bleach per one gallon of water, not five gallons, which is an unnecessary amount). Bleach will also pit glass or stainless steel, so it is not advisable to soak bleach for extended periods of time in things like glass carboys or stainless steel kegs.