Abstract for the AWWA
2009 Water Quality and Technology Conference
Abigail F. Cantor, P.E.
Chemical Engineer
Process Research Solutions, LLC
Madison, WI 53705

In Dr. Deming’s Footsteps: Distribution System Water Quality Control and Process Improvement

This presentation describes how to control the quality of distribution system water. It also shows how this technique provides opportunities to optimize water utility operations, facilitating the delivery of both safe and economical drinking water.

The path to achieving high water quality comes indirectly from Dr. W. Edwards Deming, the industrial process improvement expert of the Twentieth Century, who transformed industrial operational procedures, improving the quality of industrial products. His basic tool was a graph developed by his mentor, Dr. Walter Shewhart, called a “control chart”.

Three Wisconsin water utilities are on the forefront of using control charts in the drinking water industry for water quality control. The utilities started by using standardized monitoring stations to routinely and accurately sample water in the otherwise chaotic distribution system. The monitoring station was described at the 2008 Water Quality and Technology Conference in a presentation titled, “Pipe Loop on Steroids! A New Approach to Monitoring Distribution System Water Quality”. With the ability to routinely monitor the distribution system water economically, water utility managers now have a steady stream of various water quality data available to them. As the water quality parameter values are plotted on graphs, simple calculations can turn these time-series graphs into control charts.

With control charts, it becomes quickly evident if the water quality in a system is starting to move outside desired boundaries and action can be taken immediately before consumers’ health is threatened or before drinking water regulations are violated. In addition, control charts can be used to change water system operations so that there is less variation of certain water quality parameters and so that desired goals for water quality parameters can be achieved. For instance, the dosage of a treatment chemical can be lowered until the desired main treatment effect is still ensured while minimizing side effects and chemical costs.

This presentation shows how the three water utilities used the standardized monitoring stations and control charts to select proper corrosion control chemicals, optimize the dosage of corrosion control chemicals, optimize the pH of the water system, optimize the disinfection dosage for proper system biostability, successfully complete a switch from chlorine to chloramine disinfection, and stay in compliance with the Lead and Copper Rule.

This technique replaces decision-making based on anecdotal evidence and unproven assumptions with a new perspective of operational decision-making based on actual measurements and tracked with quantifiable results. It provides a means to optimize operations and minimize expenses – all while recording the quality of water delivered to customers.