This e-book explains a system to detect oil pollution in water based on an optical method. Various LEDs and photosensors are used as the light sources and detectors. Node-RED (an IoT platform) is used for proper display and analysis. The e-book reviews oil pollution in water, methods to sense oil pollution, and introduces an optical method to detect oil in water. The findings are discussed and can contribute to the development of advanced systems for sensing oil pollution in water viscosity. The system addresses the critical issue of oil pollution in agriculture and supports sustainable farming practices by enabling real-time monitoring and swift response to oil spills. It holds potential to protect the environment from the harmful effects of oil pollution. Prompt detection allows for immediate action to mitigate environmental impact, preventing the spread of oil and its detrimental effects on water quality and ecosystems