The researchers designed a tool to measure water turbidity in the Martapura River using a sensor and Arduino Uno R3. Turbidity is caused by particles in water scattering light, affecting its clarity. Clean water should have a turbidity value of 25 NTU. The tool accurately measured turbidity levels, showing that the river water had high turbidity before filtration but met the quality standard after filtration. This means the water can now be safely used for hygiene purposes.