**7. Conclusions and discussion**

Due to the fact that homeowners have an important stake in finding plumbing systems appropriate for their households, they should not only rely on expert advice, but also

As in the previous model specifications, Material A is the most preferred plumbing material when the CA data is estimated, employing an Ordered Logit Model with and without socioeconomic characteristics. Material C is the least preferred plumbing material. Two plumbing material attributes are important in making the decision on type of pipes to be installed in a house: 'plumbing material installation time' and 'corrosion risk'. The regression coefficients as well as the computed odds ratios and probability estimates differ

For example, for Material A, the odds ratios are lower for all preference categories in the case of model specification with socioeconomic variables, category 'Very Strongly Preferred' has odds ratios ranging from 9.034 to 14.083 for model without socioeconomic variables and 7.522 for model including socioeconomic variables. This finding implies that the socioeconomic variables impact the discrimination level between the plumbing material preference valuations. For example, if a household has experienced previous cost of plumbing repairs and/or replacement, their preference valuation level is lower for a more corrosion prone

The marginal distribution of probability estimates (Table 13) has higher values for lower preference categories for Material C in the case of model specification without socioeconomic variables. For example, for Material C, 'Not Preferred' has probability distribution estimate ranging between 0.476 compared to 0.463 (with socioeconomic variables). The marginal distribution estimates for higher preference valuation categories are lower for Material A and B for model without socioeconomic variables. For example, for Material A, 'Extremely Preferred' has a probability distribution estimate ranging from 0.074 (without socioeconomic) compared to 0.117 (with socioeconomic variables). As a result, the inclusion of socioeconomic variables raises the level of preference for Materials A and B,

In conclusion, although the inclusion of socioeconomic variables does not change the final preference ranking of the plumbing materials, it increases the estimated level of preference for Material A (epoxy coating) and Material B (plastic) by increasing the marginal probability distribution of estimates for the higher preference categories (i.e. 'Strongly Preferred'). The increase is the most pronounced in the case of Material A (model with socioeconomic variables) for which the 'Extremely Preferred' category has a probability distribution estimate almost twice as large compared to the model specification without socioeconomic variables (0.117 vs. 0.074). The respondent's previous cost of plumbing material repairs and replacement impacts positively the preference level for plumbing materials described by 'corrosion proof' attribute level. This finding implies that Materials A and B are more highly preferred when socioeconomic factors are taken into consideration. Households experiencing high costs of fixing corrosion related damage in the past are more likely to prefer and choose materials with lower corrosion levels. The decreased corrosion level implies lower future plumbing material failures, and therefore, lower costs associated

Due to the fact that homeowners have an important stake in finding plumbing systems appropriate for their households, they should not only rely on expert advice, but also

between the model specification with and without the socioeconomic variables.

plumbing material compared to material with an attribute level of 'corrosion proof'.

while it decreases the level of preference for Material C.

with repairs of water-related damage.

**7. Conclusions and discussion** 

acquire information on plumbing material attributes such as price, health impact, longevity, and corrosion resistance in order to make informed investment decisions about plumbing systems for their homes. Information on consumer preferences for drinking water plumbing attributes can be useful not only to individual households, but also to policymakers, program managers, water utilities, and firms with interests in drinking water infrastructure.

This chapter addressed the issues of household plumbing material decisions. The information was elicited by two surveys of residents residing in a Southeastern Community in the U.S. The first survey elicited information on the prevalence of pinhole leaks and other plumbing material failures, households' experiences with plumbing material failures, the cost of repairs and property damages due to the material failures, and household preferences for corrosion preventive measures. The follow-up survey, sent only to those residents who agreed to participate in future studies related to the plumbing material issues, elicited information on households' preferences for a set of hypothetical plumbing materials.

Overall, the Southeastern Community survey revealed high level of awareness of pinhole leak problem among residents of the community. Twenty percent of the households reported actual pinhole leak incidents. The percent of pinhole leak reports was on par with other hotspot areas of corrosion in the U.S., but above the rate of pinhole leak occurrences in non-hotspots (Scardina et al., 2007). The pinhole leak problem was more prevalent in houses built before the 1990s with copper pipes installed as the plumbing system. This finding is in an agreement with a Maryland Pinhole Leak Survey conducted by Kleczyk and Bosch in 2004.

The total repair expenses due to the pinhole leaks varied between \$100 and \$5,000 with several reports of more than \$5,000 in repairs. Similar results were found by Kleczyk et al. (2006) of selected communities in the East, Southeast, Midwest, and West regions. Over 50% of surveyed respondents spent more than \$100 on repairs with estimates as high as \$12,000. In comparison, in their Maryland Pinhole Leak Survey, Kleczyk and Bosch (2008) found costs from the plumbing material failure repairs as high as \$25,000. Unlike the present survey, however, the study by Kleczyk and Bosch (2008) did not separate the costs associated with pipe failure and property damage. This Southeastern Community survey accounted for this factor, which might have resulted in the differences between the two studies. Furthermore, many households in the Southeastern Community cited using a preventive measure against corrosion, including whole house re-plumbing and installation of water softeners. Over 80% of residents of the Southeastern Community were satisfied with the water quality in their homes.

The follow-up survey data of residents in the Southeastern Community revealed that among three hypothetical plumbing materials (A, B, and C), the households preferred Material A (epoxy coating) followed by Material B (plastic). Material C (copper) was the least preferred material in the set. This result was derived based on each of the respondents' preference evaluation of the different plumbing material groupings. The preference ranking of the materials was the same across both Ordered Logit model specifications (with and without socioeconomics variables). Furthermore, the results were

Households' Preferences for Plumbing Materials 445

drinking water infrastructure, as well as their chemical and physical interactions with

For example, Edwards et al. (2004) suggested that removal of natural organic matter mandated by tighter EPA drinking water standards contributed to the pinhole leak problem in combination with other factors, including faulty installation, since natural organic matter is an inhibitor to the corrosion-inducing chemical reactions. To deal with this problem, Bosch et al. (2006) found that almost 60% of water utilities added corrosion inhibitors, such as phosphate to water treatment. The inhibitors were added to protect water service lines, to comply with the lead and copper rule proposed by EPA, and to give protection to residential customers. Similarly, after adding phosphate to the water treatment process by utility companies who distribute water to the Southeastern Community, the Southeastern Community reported a decrease in the number of pinhole leak reports (Scardina &

Furthermore, the cost associated with employment of different prevention options as well as the convenience of installation has an impact on households' decisions, concerning choosing a plumbing material for their houses. As a result, service providers (i.e. plumbers and material manufactures) should be sensitive to households' financial constraints and convenience of plumbing installation for homeowners. For example, 33% of Southern Community respondents with pinhole leaks spent at least \$500 repairing damaged plumbing material, while more than 75% of survey participants with pinhole leaks experienced at least moderate level of stress. In their Maryland study of pinhole leak corrosion, Kleczyk and Bosch (2008) estimated the total cost11 of fixing damage related to pinhole leaks to range from roughly \$1,300 to more than \$18,000. As a result, when plumbing services are expensive, the service providers should concentrate on installing plumbing materials that are convenient to install, and present a low failure rate to minimize

Finally, water professionals and policy makers should work on public policy that would address public preferences for drinking water infrastructure. Results of this Southeastern Community analysis can provide information to policy experts and water utility managers who are dealing with extensive corrosion problems in their areas. Information will fill the gaps of knowledge about corrosion occurrences, the financial impact of plumbing material repairs on households, and households' preferences for drinking water infrastructure, as

The authors would like to acknowledge the financial support provided by the National Science Foundation under the grant DMI-0329474 and the American Water Works Association Research Foundation under the project #3015. The views expressed in this report are those of the authors, and not of the National Science Foundation nor of the American Water Works Association Research Foundation. In addition, the authors would like to thank James R. Strout, the Book Review Board, as well as InTech Editors for

well as the ability of householders to pay for different corrosion prevention options.

future financial outlays spent on plumbing material repairs.

providing comments, and editing earlier versions of this chapter.

11 Total cost of repairing pinhole leak damage includes the financial and time costs.

chemicals used to treat drinking water.

Edwards, 2007).

**8. Acknowledgements** 

in agreement with the survey baseline method, which ranked Material A as the most preferred and Material C as the least preferred. The baseline ranking of plumbing materials was obtained from households' comparisons of all three plumbing materials at the same time.

The plumbing material attributes that were important in the decision-making process included: 'corrosion risk' and 'time length of plumbing material installation.' In both cases, the attribute level rankings were in agreement with the transitivity assumption of preferences, and the lower corrosion risk attribute level, as well as shorter amount of time required for plumbing material installation was more preferred to the more corrosion risk prone and longer installation period attribute levels.

Only one socioeconomic variable had a statistically significant impact on the chosen plumbing material: 'cost of plumbing material repairs and replacement incurred by the respondent.' This variable was statistically influential when interacted with corrosion attribute levels. Although it did not change the preferences for plumbing materials, the variable skewed the preference valuations favorably towards plumbing materials described by 'corrosion proof' attribute level. This finding implies that the more each household had previously spent on repairs associated with plumbing material failures, the more they preferred a plumbing material with lower corrosion level to avoid future expenditures on drinking water system repairs.

There are several implications for further research that would improve the analysis of preferences for plumbing materials. The information set of plumbing material attributes might not have been the most complete and objective description of the pipe characteristics. Households with copper plumbing materials installed in their houses were more likely to identify Material C as copper (as noted on their questionnaires returned to the researchers), and therefore, might have evaluated it based on their experiences and not based on the comparison with other plumbing materials. This finding, however, is not unexpected, as part of the research question was to examine the impact of previous experiences with plumbing material failures on household decisions for corrosion prevention and plumbing material choices. Furthermore, in his AHP study, Lee (2008) noticed that some of the householders in this community provided a high degree of preference for a specific plumbing material in the survey, but in reality installed other types in their homes (Lee, 2008). As a result, in some cases, there is a mismatch between the stated preferences derived based on the homeowners' survey and the actual behavior exhibited by the households.

The above survey results inform policy makers, utility managers, and home plumbing systems producers on the homeowners' preferences for plumbing materials, and the tradeoffs between the risk of corrosion and cost of a leak-free environment based on their experiences with pipe failures in the past. The cost of alternative preventive measures, corrosion risk, and convenience of plumbing material installation drive the decisions of homeowners regarding their plumbing system. As a result, policy makers should take into consideration the implications of new federal and state regulations on the interactions between drinking water and drinking water plumbing. Furthermore, their regulations and standards should accurately test the different types of plumbing materials used in the

in agreement with the survey baseline method, which ranked Material A as the most preferred and Material C as the least preferred. The baseline ranking of plumbing materials was obtained from households' comparisons of all three plumbing materials at

The plumbing material attributes that were important in the decision-making process included: 'corrosion risk' and 'time length of plumbing material installation.' In both cases, the attribute level rankings were in agreement with the transitivity assumption of preferences, and the lower corrosion risk attribute level, as well as shorter amount of time required for plumbing material installation was more preferred to the more corrosion risk

Only one socioeconomic variable had a statistically significant impact on the chosen plumbing material: 'cost of plumbing material repairs and replacement incurred by the respondent.' This variable was statistically influential when interacted with corrosion attribute levels. Although it did not change the preferences for plumbing materials, the variable skewed the preference valuations favorably towards plumbing materials described by 'corrosion proof' attribute level. This finding implies that the more each household had previously spent on repairs associated with plumbing material failures, the more they preferred a plumbing material with lower corrosion level to avoid future expenditures on

There are several implications for further research that would improve the analysis of preferences for plumbing materials. The information set of plumbing material attributes might not have been the most complete and objective description of the pipe characteristics. Households with copper plumbing materials installed in their houses were more likely to identify Material C as copper (as noted on their questionnaires returned to the researchers), and therefore, might have evaluated it based on their experiences and not based on the comparison with other plumbing materials. This finding, however, is not unexpected, as part of the research question was to examine the impact of previous experiences with plumbing material failures on household decisions for corrosion prevention and plumbing material choices. Furthermore, in his AHP study, Lee (2008) noticed that some of the householders in this community provided a high degree of preference for a specific plumbing material in the survey, but in reality installed other types in their homes (Lee, 2008). As a result, in some cases, there is a mismatch between the stated preferences derived based on the homeowners' survey and the actual behavior

The above survey results inform policy makers, utility managers, and home plumbing systems producers on the homeowners' preferences for plumbing materials, and the tradeoffs between the risk of corrosion and cost of a leak-free environment based on their experiences with pipe failures in the past. The cost of alternative preventive measures, corrosion risk, and convenience of plumbing material installation drive the decisions of homeowners regarding their plumbing system. As a result, policy makers should take into consideration the implications of new federal and state regulations on the interactions between drinking water and drinking water plumbing. Furthermore, their regulations and standards should accurately test the different types of plumbing materials used in the

the same time.

prone and longer installation period attribute levels.

drinking water system repairs.

exhibited by the households.

drinking water infrastructure, as well as their chemical and physical interactions with chemicals used to treat drinking water.

For example, Edwards et al. (2004) suggested that removal of natural organic matter mandated by tighter EPA drinking water standards contributed to the pinhole leak problem in combination with other factors, including faulty installation, since natural organic matter is an inhibitor to the corrosion-inducing chemical reactions. To deal with this problem, Bosch et al. (2006) found that almost 60% of water utilities added corrosion inhibitors, such as phosphate to water treatment. The inhibitors were added to protect water service lines, to comply with the lead and copper rule proposed by EPA, and to give protection to residential customers. Similarly, after adding phosphate to the water treatment process by utility companies who distribute water to the Southeastern Community, the Southeastern Community reported a decrease in the number of pinhole leak reports (Scardina & Edwards, 2007).

Furthermore, the cost associated with employment of different prevention options as well as the convenience of installation has an impact on households' decisions, concerning choosing a plumbing material for their houses. As a result, service providers (i.e. plumbers and material manufactures) should be sensitive to households' financial constraints and convenience of plumbing installation for homeowners. For example, 33% of Southern Community respondents with pinhole leaks spent at least \$500 repairing damaged plumbing material, while more than 75% of survey participants with pinhole leaks experienced at least moderate level of stress. In their Maryland study of pinhole leak corrosion, Kleczyk and Bosch (2008) estimated the total cost11 of fixing damage related to pinhole leaks to range from roughly \$1,300 to more than \$18,000. As a result, when plumbing services are expensive, the service providers should concentrate on installing plumbing materials that are convenient to install, and present a low failure rate to minimize future financial outlays spent on plumbing material repairs.

Finally, water professionals and policy makers should work on public policy that would address public preferences for drinking water infrastructure. Results of this Southeastern Community analysis can provide information to policy experts and water utility managers who are dealing with extensive corrosion problems in their areas. Information will fill the gaps of knowledge about corrosion occurrences, the financial impact of plumbing material repairs on households, and households' preferences for drinking water infrastructure, as well as the ability of householders to pay for different corrosion prevention options.
