A STUDY FOR THE APPLICATION OF STATISTICAL PROCESS CONTROL CHARTS IN DRINKING WATER QUALITY INDICATORS

The water supply in terms of quantity and quality is a growing concern. Water quality has been compromised since the spring, because of the discharge of effluents, which requires investment in treatment plants to ensure the quality of the water supplied. The water leaving treatment plants to the distribution network must achieve the specification for some parameters set in legislation. But in addition to meeting these limits, to maintain the quality of the water supply it is also important to assess the variability. In this sense, statistical control charts play an important role. The main objective of this paper is to analyze the application of statistical control charts for turbidity and residual chlorine, two indicators of the quality of drinking water. The data, both turbidity and residual chlorine, were autocorrelated, and it was necessary to apply specific techniques to solve this problem. Shewhart control charts for individual measures with extended limits extended and applied to residuals from an ARIMA model, were analyzed in this study. These proposals were adequate to monitor these parameters.