Water turbidity is one of the parameters used to determine water quality standards. Water turbidity is caused by the presence of organic and inorganic materials contained in water such as mud and fine sand. The amount of turbidity is determined by a value called the Nephelometer Turbidity Unit (NTU). The maximum level allowed for drinking water is 5 NTU. The higher the NTU value, the more turbid the water will be and it will greatly affect water quality. So that the water consumed by the community is not cloudy and does not contain ingredients that cause bacteria to occur, it is made "Portable Turbidimeter equipped with Arduino-based data storage". This tool is designed using photodiode sensors that will receive light from LEDs and ATmega 328 as data processors. Based on the results of turbidity measurements that have been done, the highest error value is 0.9989%. After testing the system as a whole, the tool can be used with its functions and objectives.