Plumbing Materials: Impacts on Drinking Water Quality and Consumer Willingness to Pay Civil & Environmental Engineering: Andrea Dietrich, Marc Edwards, G. V. Loganathan … Food Science and Technology: Susan Duncan

Agriculture and Applied Economics: Darrell Bosch … Institute for Community Health: Sharon Dwyer … Virginia Water Center: Tamim Younos … Biological Sciences: Joseph Falkinham

PhD Students: J. Cerrato, J. H. Hong, E. Kleczyk, J. Lee, P. Omur-Ozbek, E.Tanellari, Y. Zhang MS Students: J. Cuppett, A. Dudi, M. Durand, A. George, T. Heim, H. Johnson, J. Ladd, N. Murray, C. Nguyen, S. Triantafyllidou

Undergraduate Students: S. Abbot, A. Galvis, M. Greenfield, J. Nicholson, K. Robbins, A. Strickhouser, Montana State University, Civil & Environmental Engineering: Anne Camper

Interdisciplinary Connections

Economics

Aesthetics/Analyt. Chem

Consumer/Health Issues

Chem./Biol.Causes

CORROSION!!

Fundamental Science

New Models for Plumbing

Det

ectio

n / P

erce

ptio

n

Fears? Facts?

Risk C

omm

unicatio

n

Costs ofMaterials, Treatments,Regulations?

cPVC HDPE PEX-a PEX-b Epoxy

gasoline-like pleasant-sweet alcohol sweet, burning, chemical sweet-tarry

sweet-tarry citrus, floral bad, aldehyde model, glue

hydrocarbon bad, aldehyde sweet solvent

gasoline/terpentine citrus, floral

OVERVIEW: Our interdisciplinary study of materials used in drinking water infrastructure answers inextricably interwoven questions about drinking water conveyance, quality of water at the tap, and “real” costs of household plumbing. Our multi-prong approach integrates: Biochemistry of Materials Degradation and Water Quality, Aesthetics and Analytical Chemistry of Corroded Materials, and Economics, Health and Perception in Consumer Decision-making. A portion of our results are presented here, including: 1) fundamental understanding of chemical corrosion and human response to copper in drinking water; 2) an understanding of how changes in disinfectant type and natural organic matter (in response to current EPA regulations) will alter materials performance to impact water quality, biological stability and aesthetics; and 3) gaining consumer input on home plumbing and its failures. Other aspects of this project include investigating lead in drinking water, evaluating microbial growth in pipes and hot water heaters, and development of tools for use by policy makers and citizens to make informed decisions.

NSF # DMII 0329474

Consumer Health and Aesthetic Issues

Costly Repairs and Water Losses

1. Copper Corrosion, Flavor, and HealthWe discovered that people taste soluble copper but not copper particles, which readily form in drinking water. Copper interacts with salivary proteins, has astringent, bitter and metallic tastes, and produces a retronasal smell. As the copper concentration increases and more particles form, people are not able to detect the flavor even as it approaches levels that cause illness.

Parameter

(short term testing)Plumbing Material

cPVC HDPE PEX-a PEX-b Epoxy Copper

Increased Odors –

sensory annoyance

1 5 2 5 3 3

Organic Carbon Release –

food for microorganisms

1 1 2 5 3 1

Chlorine Consumption –

loss of disinfectant

1 2 1 1 5 5

Chloramine Consumption-

loss of disinfectant

1 2 1 1 5 5

Microbiological Growth 2 3 3 3 2 2

3. Impacts on Consumer Willingness to PayBetween 45 and 50% of those interviewed were willing to pay an “additional” positive amount for leak-free plumbing materials, with Midwest having the highest percentage. Those who were unwilling to pay more varied from 25 to 30%.

Additional

Amount Willing

to Pay ($)

% Interviewees by Geographical RegionSoutheast Mid West West Rest of

U.S.U.S. Total

0 24.8 27.5 30.3 27.2 27.5

500 2.8 4.6 4.6 4.4 4.4

600 5.5 6.4 4.6 6.4 6.2

700 5.5 5.5 5.5 7.5 7.3

800 7.3 13.8 5.5 10.2 9.6

1200 8.3 4.6 12.8 7.9 8.5

2000 3.7 8.3 5.5 6.2 6.1

4000 11.9 7.3 8.3 4.4 4.9

Don’t Know 28.4 22.0 22.9 25.8 25.5

No Answer 1.8 0 0 0 0

ODORS

WATERQUALITY 1= minor 5= major impact

COSTS

Materials Scienceand Performance

2. Impact of Plumbing on Odor and Quality of Drinking WaterIn short-term leaching test for the plumbing materials, cPVC imparted the fewest organic compounds to the water, consumed the least amount of disinfectant, and had few noticeable odors. All other polymer materials imparted distinct odors and organic chemicals, and consumed residual disinfectant. Copper pipe consumed nearly all the residual disinfectant. These effects were most prominent in the first 2 months of material use.

70 73 78

0102030405060708090

100

0 0.1 0.25 0.5 1 1.3 2 3 4 6 8 >8

mg/l of total copper

Cu

mu

lati

ve %

of

det

ecti

on

00.20.40.60.811.21.41.61.82

mg

/l o

f s

olu

ble

co

pp

er

EP

A A

ctio

n L

eve

l _

WH

O G

uid

elin

e

EP

A S

MC

L

Ga

stro

inte

stin

al i

llne

ssFLAVOR and

HEALTH

Region where 50%population can detect

Some people never taste copper

SUMMARY: This interdisciplinary project evaluates interactions of plumbing and water quality to provide science in support of consumer health and concerns. The results will inform the water industry, researchers, regulators, and the public on mechanisms to improve drinking water palatability and safety.