The contamination of natural waters by both biological and chemical contaminants is a worldwide problem and Puerto Rico country isn't the exception. The use of Hypochlorus Acid (HOCl) in the water disinfection process can cause a water drinking problem during storage and the transmission to the consumer by adding a small excess of the chemical. The most important contaminants commonly present in drinking water are the trihalomethanes (THMs), phenols, amines, and phthalates.

A special attention has been made in this research to the presence of trihalomethanes (THMs). The compound chloroform (CHCl₃) is suspected to be a liver carcinogen in humans and have negative reproductive and development effects. The Environmental Protection Agency (EPA) under the Clean Water Act (CWA) have set standard for Total THMs in drinking water of 80 parts per billion as the Maximum Concentration Limit (MCL). The analytical method used to determine the volatile organic compounds (VOC's) in the selected potable water was the Solid Phase Micro-Extraction (SPME) and Gas Chromatography using a Mass Spectrometry Detector (GC/MS). The first step was the validation of the SPME fiber for the quantification of chloroform. This preliminary research results shows that the most abundant VOC's compounds was chloroform in the South and West Area of the island.