Full formScience
THMstands forTrihalomethane
Full Form of THM
What is THM?
Trihalomethane (THM) is a collective term for a group of chemical compounds that form when chlorine or other chemical disinfectants used in water treatment react with natural organic matter present in the source water. The four primary compounds classified under THMs are chloroform, bromoform, bromodichloromethane, and dibromochloromethane. In India, THMs are a significant concern because the country relies heavily on chlorine-based disinfection of municipal water supplies to combat waterborne diseases. Long-term exposure to elevated THM levels has been linked to liver, kidney, and central nervous system issues, making it an important parameter monitored by the Central Pollution Control Board and the Bureau of Indian Standards. The Indian drinking water specifications set the maximum permissible limit of total THMs at 100 micrograms per litre, aligning with WHO guidelines. THM testing is routinely performed in water treatment plants across metropolitan cities and is studied extensively in civil engineering, environmental science, and public health courses. Understanding THM formation and removal techniques is essential for students preparing for competitive examinations such as GATE, UPSC, and state public service commissions where water treatment and environmental management form part of the syllabus.
THM का फुल फॉर्म
ट्राइहैलोमीथेन
Example
The municipal water utility in Chennai reported that the total THM concentration in treated water had crossed the permissible limit set by the BIS, prompting immediate modifications to the chlorination process.
THM — frequently asked questions
What is the full form of THM?
THM stands for Trihalomethane, a group of chemical compounds formed when chlorine reacts with organic matter in water during treatment.
Is THM harmful to human health?
Yes, prolonged exposure to high levels of trihalomethanes has been linked to liver, kidney, and central nervous system problems, and they are classified as probable human carcinogens.
What is the permissible limit of THM in drinking water in India?
The Bureau of Indian Standards has set the maximum permissible limit of total THMs in drinking water at 100 micrograms per litre, in line with WHO guidelines.
How are trihalomethanes formed in water?
Trihalomethanes form as disinfection by-products when chlorine or other chemical disinfectants react with natural organic matter such as humic and fulvic acids present in raw water.