The term 'DIGITAL Water Tester' is a device used to measure the quality of water. It is composed of two parts: TOE, which stands for Total Organic Carbon, and DIGITAL, which refers to the electronic components used to measure the organic carbon levels. The device is used to detect the presence of organic compounds in water, such as bacteria, viruses, and other contaminants. This information can then be used to determine the safety of drinking water or to identify sources of pollution.