Health and Social Benefits of Pathogen Reduction by Drinking Water Treatment

Principal Investigator - Diane Dupont, Professor, Brock University, 2001 - 2004

Challenge

Waterborne pathogens in the environment are a constant threat to Canadian drinking water sources. Inadequate treatment, accidents, and natural disasters are all risks for these pathogens to reach the population and cause illness or disease. Water utilities may adopt a number of approaches to reduce the health risks from pathogens, each involving varying costs and success rates.  While engineering cost estimates for new systems are available, very little is known about how Canadian consumers view the safety of their drinking water and the values that they place upon being able to obtain improved health benefits from reduced risks of pathogens.

This project was designed to determine the extent to which consumers would be willing to pay higher prices for better quality drinking water that reduces their exposure to the pathogens and other potentially harmful compounds in tap water. This information was then used to conduct a cost-benefit analysis of alternative water treatment technologies. The key end users of the project are water utilities and municipal governments responsible for drinking water infrastructure, supply and wastewater treatment to design more efficient water and sewage infrastructure investments and pricing decisions.

Project

The first component of the study was a series of focus groups in four Canadian cities, examining participants’ perceptions of the health risks associated with pathogens in municipally supplied tap water and their willingness to pay for improved drinking water quality. The study used two example scenarios; the presence of microbials which can cause illnesses and possibly deaths and the presence of trihalomethane, a chlorine disinfection by-product implicated in increased rates of bladder cancer.

The researchers then implemented a Canada-wide Internet-based survey, gathering responses from over 1600 participants with proportional representation from across the country. To obtain underlying consumer preferences, researcher used Contingent Valuation, a commonly employed valuation method, They contrasted this with a new approach; Attribute Based Stated Choice Method (ABSCM). Among their results, they found that 18% of Canadians feel their tap water poses a moderate to serious health risk and over half perceive bottled water as a safer alternative. Survey results also provided an estimation of what the average household is willing to pay to achieve health risk reductions related to bladder cancer and microbial illness over a 35 year time horizon.

Data on the marginal willingness-to-pay values were used to derive two types of measures to evaluate alternative health policy decisions – value of statistical illness (VSI) and value of statistical life (VSL).  Researchers also collected information on the costs of various disinfection options for municipally supplied water, and used these costs in conjunction with the benefits estimates from the survey to complete a cost-benefit analysis of disinfection methods.

Outputs

• Development of a report for Health Canada outlining the findings and identifying different methods that could be used to obtain willingness-to-pay (benefits) values of representative Canadians for stated improvements to municipally delivered water.

• Contribution to a publically available Discussion Paper on the results through the Resources for the Future, a non-profit and nonpartisan organization for independent research.

• Creation of multiple presentations to disseminate the research findings to fulfill their goal of reaching a target audience of regulators and operators.

• Development of software templates for pricing and infrastructure investment decisions by water and sewage treatment facilities, which included demand and risk parameters that can be modified to suit different conditions.

Select Publications

Adamowicz, V., Dupont, D., Krupnick, A., and Zhang, J. (2007) “Valuation of Cancer and Microbial Disease Risk Reductions in Municipal Drinking Water: An Analysis of Risk Context Using Multiple Valuation Methods” Resources for the Future Discussion Paper 07-39. July 2007. 34 pp.

Adamowicz W., Diane Dupont, and Alan J. Krupnick (2004). “The Value of Good Quality Drinking Water to Canadians and the Role of Risk Perceptions: A Preliminary Analysis” Journal of Toxicology and Environmental Health, Part A 67(20) 1825-1844.

Dupont, D. P. (2005) “Tapping into Consumers” Perceptions of Drinking Water Quality in Canada: Information to Assist Utilities to Better Manage Their Operations”, Canadian Water Resources Journal. 30(1):11-20.

Dupont, D. P.  and S. Renzetti (2008) “Good to the Last Drop? An Assessment of Canadian Water Value Estimates” Canadian Water Resources Journal. 33(4):363-374.

Zhang, J., Adamowicz, W., Dupont, D.P. and Krupnick, A. 2013 “Assessing the Extent of Altruism in the Valuation of Community Drinking Water Quality Improvements” Water Resources Research. 49:6286-6297.

Dupont, D. P.  and Jahan, N. 2012 “Defensive Spending On Tap Water Substitutes: The Value of Reducing Perceived Health Risks” Journal of Water and Health. 10(1): 56-68.

Adamowicz, W., Dupont, D.P., Krupnick, A., and Zhang, J. 2011. “Valuation of Cancer and Microbial Disease Risk Reductions in Municipal Drinking Water: An Analysis of Risk Context Using Multiple Valuation Methods” Journal of Environmental Economics and Management.  61(2):213-226.

Dupont, D. P., Adamowicz, W.L., and Krupnick, A. 2010. “Differences in Water Consumption Choices in Canada: the Role of Socio-demographics, Experiences, and Perceptions of Health Risks” Journal of Water and Health. 8(4): 671-686.

Select Presentations

2008  “The Role of Altruism in the Valuation of Community Drinking Water Risk Reductions” (with J. Zhang, V. Adamowicz and A. Krupnick) presented at 18th annual meeting of the Canadian Resource and Environmental Economics Study Group, Ryerson University, October 3-5.

2006 “Consumer Perceptions of Municipal Drinking Water Quality” Invited presentation to the annual conference of the Ontario Branch of the Canadian Institute of Public Health Inspectors. Niagara Falls, Ontario, September 13, 2006.

2006 “Drinking Water Quality and Climate Change: What Are Consumers Willing to Pay to Reduce Health Risks” (with V. Adamowicz and A. Krupnick) at the University of Guelph, Department of Agricultural Economics and Business

Seminar series. January 13, 2006.

2004 “Value of Good Quality Drinking Water to Canadians” Presentation made to the Canadian Water Network’s Summer Watershed Workshop 2004. June 1, 2004. Renison College, University of Waterloo.

Outcomes

• Increased awareness as this research represents the first survey of its kind in Canada to provide background information on experience with tap water problems, awareness of presence of microbials in tap water, expenditures on tap water substitutes, concerns regarding the relationship between tap water and health, and willingness-to-pay (benefits) values for improved tap water.

• Informed decision-making as one of the key project goals was to provide data to all levels of government to make scientifically sound decisions on the difficult choices a society has to make between conflicting demands for public investment. The value of statistical illness (VSI) and value of statistical life (VSL) represents an important enhancement to the work previously done in this area, and improvement on the tools available to evaluate alternative health policy decisions.

• This project determined willingness-to-pay measures which can contribute to the design of more efficient water and sewage infrastructure investments and pricing decisions. The uptake of this information will ultimately lead to a lower incidence of negative health outcomes and a reduction in the demands placed upon Canada’s health care system.