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TOC & Water Analysis

TOC stands for total organic carbon in water. Sounds innocuous enough but when water contains high levels of organic carbon it can make ingestion of the water toxic. There are naturally occurring carbon compounds in water but the ones we care most amount are the ones that pose a health threat when we drink it. Carbon compounds include insecticides, herbicides and other agricultural chemicals that enter drinking water sources from rain runoff or from discharges from industrial waste, accidental spills or leaks.. In any event, we don't want to drink it or ingest it for fear of sickness or death. So before water goes into our system from municipal water systems, commercially produced bottled water, pharmaceutical water or any other source it is tested to make sure it is safe.

  1. TOC is a Measure of Toxicity

    • Simply put, the more carbon organic content, the more oxygen in the water is consumed by an increase in growth of microorganisms, which further adds to the depletion of oxygen in the water. The source of the organic material occurs naturally but it is introduced into water through man-made sources such as industrial waste water, which may not be completely removed by treatment. The Clean Water Act of 1974 set standards for potable for human consumption and the safe conditions for aquatic life and pharmaceutical use. The best way to measure the toxicity is to determine the total organic carbon.

    Simplified

    • It's a formula. The TOC are the proteins, sugars, fats and alcohol combinations and there are many ways they join together that come from the total carbon minus the total inorganic carbon plus the volatile organic compounds plus the organic compounds that cannot be purged from the water. There are several methods to determine the TOC. They sound highly technical but since refinements in the 1970s the various tests are relatively simple and accurate.

    Testing

    • To define the accuracy of analysis the water is put through a process of oxidation which converts the organic compounds to carbon dioxide either by heating it to almost 2,000 degrees, chemically, or using ultraviolet radiation. The efficiency of this method assures the complete conversion of organic carbon to carbon dioxide, which can then be measured by a CO2 detector which measures the amount of gas. The amount of gas directly correlates to the organic carbon content of the water.

    In Europe

    • There are primarily two other competing systems in Europe. One is the expulsion method and the other is the difference method. The composition of the water sample determines the method use. While regulatory agencies in Europe accept either method, the results may vary widely depending on the composition of the water that is tested. For example, if there is a high concentration of volatile organic compounds, they will not show in the results of the expulsion method. Therefore, water content will be the determining factor of which method is best.

    What next?

    • The Safe Drinking Water Act as amended in 1987 requires less than 5 parts per billion of Total Organic Compound. When amounts are above that level, the water must be treated using various methods, including chemicals, to reduce the TOC levels to what prescribed safe drinking levels. The most commonly used chemical is chlorine because it is an effective disinfectant for viruses and bacteria, and it disinfects water as it travels through pipes to your home. That is why, unless the balance is just right, people often complain of a chlorine taste to their municipal drinking water. Chlorine is also used in private wells for the same purpose,

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