Colored Water Causes and Control Strategies - Pilot Test Experiences of a US Water Provider

A large water provider in the Southwest United States of America (US) has been experiencing an increased number of colored water complaints during the summer months. Authors conducted a comprehensive evaluation to identify the causes for colored water and develop strategies to mitigate colored water occurrence. The evaluation included pilot tests with iron pipes harvested from the distribution system. Pilot tests were conducted to evaluate the effects of water quality (pH, alkalinity etc) and distribution system operation (pipe flow velocity and flow reversal) on the release of corrosion by-products. Alkalinity and pH were found to have a significant impact on the corrosion by-product releases. A half unit decrease in the distribution system water pH resulted in a 300 percent (%) increase in iron release and a 200% decrease in turbidity. Doubling of the pipe flow velocity resulted in 250% increase in iron release and 300% increase in turbidity. Tests were also conducted to study the benefits of corrosion inhibitor addition. Addition of dipotassium orthophosphate and stannous chloride corrosion inhibitors at low dosages reduced the iron release by approximately 40%.