Water Softening Project 

Water Softening Project 

This project will develop recommendations to modify the treatment process to provide City of Ann Arbor drinking water customers with a desirable level of water hardness.

 The Facilities Master Plan completed in 2006 identified the need for replacement of lime softening equipment.  Concurrent with designing the needed equipment replacement, the City seeks to obtain customer feedback on the desired level of hardness in the drinking water. 

 A Customer Advisory Committee will review taste, cost, operational and health considerations as well as engage larger groups of customers to help shape the final recommendations.

 Please review the information on this page to learn more about the process and findings to date. If you would like to be included in focus groups or survey outreach, please contact us.

• Water Hardness Background
• Project Overview and Timeline
• Project Team & Customer Advisory Committee

Water Hardness Background

City of Ann Arbor drinking water is considered hard, as is much of the water in the Midwest. Water hardness is the result of certain dissolved minerals in water, primarily calcium and magnesium. These minerals are naturally occurring and dissolve in water from contact with soils and rocks. City of Ann Arbor drinking water ranges between 130-180 milligrams per liter (mg/L) or parts per million (ppm) of hardness (measured as calcium carbonate).

Reference: Virginia Polytechnic University

Harder water can have these effects for customers:

• Scaling of appliances and pipes
• Potential for reduced life of hot water heaters
• Spotting on dishes in dishwashers
• Higher quantity of soap use
• Increased use of residential and business softening units
• Additional treatment costs for customers that soften their water

 Additionally, hardness affects the taste and odor of water. There are currently no regulations mandating levels of hardness in drinking water.

 Decreasing the hardness of the City’s drinking water would require an increase in the use of sodium hydroxide at the Water Treatment Plant.  Sodium hydroxide is currently used by the City as part of its treatment process to raise the pH of the water prior to filtration.  Using additional sodium hydroxide as part of the softening process has been tested full-scale at the City’s water treatment plant and has been shown to be an effective means to reduce drinking water hardness.  However, increasing the use of sodium hydroxide will increase the amount of sodium in the drinking water from the current average of 56 milligrams per liter (mg/L) to a range between 88mg/Land a maximum of 119mg/L

 While this increase in sodium intake via tap water is relatively minor, the project team will review health considerations associated with this increase with local health professionals.

 The United States Environmental Protection Agency (USEPA) does not regulate sodium.  However, some states and Canadian provinces have established their own regulations.  Those recommendations and regulations are as follows:

• USEPA recommendation: 20 mg/L
• Ontario regulatory limit: 200 mg/L
• Ontario medical notification limit: 20 mg/L
• Florida regulatory limit:160 mg/L

 Once adequate data has been collected to understand more thoroughly the costs and benefits of reducing drinking water hardness, customers will be asked to share their perspectives on the level of hardness they desire.

 Project Overview and Timeline

There are two major components to this project:

Part One includes the evaluation of options for capital improvements to the existing lime feed/slaking softening equipment to ensure worker safety and replace aging equipment at the Water Treatment Plant. This evaluation process will be completed by August 2008, followed by design and construction scheduled for completion by January 2010.

Part Two is the assessment of the operational benefits, cost and health considerations associated with decreasing water hardness through the increased use of sodium hydroxide. This work will be supported by the Customer Advisory Committee and will include the following tasks:

§         Development of information for the community      March-June 2008

§         Research in other communities regarding softening processes April- June 2008

§         Assessment of costs, operational benefits and health implications of proposed changes: April-June 2008

§         Review of feedback from customers via focus groups and survey May-July 2008

§         Develop recommendations for City Council   July-August 2008

 Project Team and Customer Advisory Committee

 This project is led by Brian Steglitz, Senior Utilties Engineer for the Ann Arbor Water Treatment Plant. He is working with a consulting team from Camp Dresser & McKee, Inc. (CDM) CDM’s project manager is Samir Mathur, assisted by Janice Skadsen.

 They are supported by a Customer Advisory Committee:

 The Customer Advisory Committee will reach out to a broader base of customers in the following ways:

• Develop web site for customer information
• Hold two focus groups: one of health interested customers and professionals and one of large customers (high water use)
• Perform a web survey of residential customers.  Offer an option of a focus group for interested survey responders.
• Develop and share a water softening fact sheet

Customer Advisory Committee meetings will be held on the following dates.  Click on the date to see meeting presentations and summaries.

• March 11
  Minutes
  Presentation
• April 15
  Minutes
  Presentation
• May 15
• June 5
• June 26