| The chlorine residual drinking water measurements | | | | measurement allowed by the EPA is 4.0mg per liter, |
| are used for two purposes. One is to make sure that | | | | almost 10 times what is necessary to provide |
| the level is high to kill bacteria. The other is to make | | | | adequate disinfection. |
| sure that the level is not too high to cause health | | | | Chlorination or other forms of disinfection are |
| problems for a person. | | | | necessary in most parts of the world. If no effort to |
| The level is measured in milligrams per liter. The mg/l | | | | disinfect was made, there would be huge outbreaks |
| necessary to kill bacteria varies according to the pH | | | | of waterborne illnesses on a regular basis. Clearly, the |
| level, the temperature and the amount of time that it | | | | effort must be made to protect the public's safety. |
| is in contact with the supply. | | | | The problem that many scientists and other |
| For example, if you had a private well, you would | | | | interested parties have is with that maximum |
| need to measure the pH level and the temperature | | | | allowable level. Why does it need to be so high? |
| of the water when it enters the house. The pH can | | | | Although the chemical is not highly toxic, it is a |
| be determined using a meter or indicator paper | | | | respiratory and eye irritant. When consumed by |
| treated with anthocyanins, a compound found in | | | | children on a regular basis, it causes anemia. |
| many plants. The anthocyanins turn red in acidic | | | | It is a skin irritant too. Showering or bathing in it can |
| solutions and blue in alkaline or "base" solutions. | | | | cause or aggravate acne, as well as cause allergic |
| The pH of distilled water is 7, which is neutral. | | | | reactions. |
| Rainwater has a pH of about 5.5, (an acidic | | | | The maximum chlorine residual drinking water |
| measurement) unless there is a great deal of pollution | | | | measurement recommended for swimming pools is |
| in the atmosphere. When pollution is present, the rain | | | | 3.0mg/l. Most people try to keep the level lower, in |
| will be even more acidic. Many wells and underground | | | | order to avoid irritated eyes and skin. |
| sources have alkali deposits, which would be | | | | The maximum that children are supposed to |
| demonstrated by a pH measurement greater than 7. | | | | consume is 2.0mg/l. Since there are a great many |
| The necessary chlorine residual drinking water | | | | children in the US population, one would think that the |
| measurement for well-water that has a 7.5 pH and is | | | | EPA would lower the allowable level. But, they have |
| 32-40 degrees Fahrenheit at the point where it | | | | yet to do so. |
| enters the house is.5 mg/l, assuming that the | | | | If you, like many of us, are concerned by the |
| disinfectant is in the storage tank for a minimum of | | | | maximum allowed chlorine residual drinking water |
| 40 minutes. Because people need to draw from the | | | | levels, you could contact your congressman. But until |
| storage tank on a frequent basis, the contact time | | | | things change, the best thing to do is to install a high |
| may need to be estimated and the amount of | | | | quality carbon filtration system in your home. Take |
| disinfectant increased. | | | | out what the treatment facility puts in, and protect |
| For residences serviced by a public treatment facility, | | | | your health. |
| the maximum chlorine residual drinking water | | | | |