What effects does chlorine have on potable water and humans?

Answer 1

Chlorine can be used to keep potable water potable. That is--it can cut down on bacteria and diseases--when used in proper amounts.

We use large plastic water coolers on our farm to provide water stations out in the field. When we fill the coolers we add about a few teaspoons to each. This assures us that our employees are able to drink water that is kept uncontaminated. This amount of bleach is not harmful, but rather beneficial.

Answer 2

Dilute mixtures of chlorine bleach and water are a common and cost-effective method for sanitizing equipment in food processing
operations. When used properly, chlorine bleach can be a very effective
method of killing undesirable microorganisms.

Processors should be aware, however, that there are regulations concerning the use of this sanitizer. The germ-killing effect in a solution of
chlorine bleach and water is due to available chlorine, present as hypochlorite and hypochlorous acid. Federal regulations (21 CFR
Part 178) permit the use of sanitizing solutions containing sodium hypochlorite on food processing equipment and food contact articles
with the following provisions:

• Equipment or articles sanitized with the solution must be allowed to drain adequately before contact with food.
• Solutions used for sanitizing equipment shall not exceed 200 parts per million (ppm) available chlorine.

About one tablespoon (1/2 fluid ounce, 15
ml) of typical chlorine bleach per gallon of water is the maximum that should be used for sanitizing food contact surfaces, according
to federal regulation. If higher concentrations are used, the surface must be rinsed with potable water after sanitizing. Contact times of
one to five minutes are usually sufficient to achieve a thorough kill, depending on chlorine concentration and organic load.

The effectiveness of chlorine as a sanitizer is determined in large part by pH. This is because when sodium hypochlorite (NaOCl) is mixed with water an equilibrium reaction between hypochlorite and hypochlorous acid (HOCl, the active sanitizing agent) occurs. This
reaction occurs as follows:
First, the NaOCl dissolves and chemically breaks apart in the water.
NaOCl + H2O OCl- + Na+ + OH- + H+
Then, the hypochlorite ion (OCl-) reacts with the hydrogen ions in the water to form hypochlorous acid.
OCl- + H+ +OH - HOCl + OH -

As seen in Figure 1 below, most of the chlorine is in the form of
hypochlorous acid. As the pH drops, another change occurs, resulting
in an equilibrium reaction between hypochlorous acid and free
chlorine. The chlorine molecules form chlorine gas (Cl2) according
to the following reaction:
HOCl + H+ + Cl - Cl2 + H2O
This is a reaction to be aware of since chlorine gas is highly toxic. For this reason, never add acid to a chlorine solution without monitoring its pH. One common source of acid is vinegar - often used as a cleaning aid. Some commercial cleaning agents are also acidic.