July 11, 2023 1:58 am

Customer perceptions of utility quality & premise plumbing both contribute to consumer choices about drinking water

trustworthy tap?

A central theme that emerges from The Profits of Distrust is that the choice to drink bottled water reflects customers’ concerns about quality of water from their utilities. One of the more frequent questions I’ve received since publishing Profits is whether concerns about premise plumbing—that is, the pipes and fixtures within people’s homes—also contributes to bottled water consumption. Do people opt for bottled water at home because they don’t trust their utility’s water quality? Or is it because their homes have old, deteriorating plumbing and lousy fixtures?

Premise plumbing problems

Traditionally, managers, regulators, and policymakers considered it the utility’s responsibility to deliver safe water to customers. That utility water gets to customer connections through main lines (“big pipes”) and a meter. But before people drink, bathe, or cook with that water, it passes through a service line, then indoor plumbing, then fixtures like faucets and showerheads. The quality of these “little pipes” on the customer’s side of the meter varies widely, and this variation in premise plumbing raises a variety of concerns about the safety of the water that people ultimately consume.

Older and lower-quality housing stock tends to have poorer premise plumbing. So a consumer might choose to drink bottled water because of concerns about her own home’s plumbing, even if she believes that her utility provides safe water. How much does quality on each side of the meter account for bottled water consumption?  

To the data!

Happily, data from the U.S. Water Alliance’s 2020 and 2021 Value of Water Survey (VOWS) offer us some leverage on this question. VOWS is a public opinion poll that surveys around a thousand U.S. citizens annually with a series of questions about their behaviors and attitudes toward water. We used some VOWS data in Profits, and I’ve blogged about a cool study of framing and support for rate increases in that survey. In 2020 and 2021 VOWS asked respondents whether they trusted their utility’s water quality with the question:

  • Do you trust that the drinking water being delivered to your home is safe?

Separately, participants were asked about the safety of their own homes’ plumbing:

  • Do you trust that the water pipes in your home are safe?

Responses to each of these questions were coded on a four-point scale, ranging from “strongly no” to “strongly yes.” Importantly, these survey data measure perceptions of safety, not actual safety. But when it comes to consumer choices, perceptions are really what count.

It turns out that there’s a lot of variation in trust on both of these measures.* Statistical analysis allows us to look at the simultaneous relationships between trust in utility water, trust in premise plumbing, and bottled water consumption. That is, we can estimate how much concerns about utility water and premise plumbing contribute to the choice to drink bottled water, while controlling for factors like gender, race, and income. Here are the results presented graphically:

Analysis of 2020-2021 Value of Water Survey data.

Trust in utility water is on the vertical axis, while trust in premise plumbing is on the horizontal axis. The light blue represents a low likelihood of drinking bottled water, with the darker blue representing higher likelihoods of bottled water consumption. As you can see, there’s significant variation on both dimensions. In fact, the correlations of both variables with the likelihood of bottled water consumption are remarkably similar. Confidence in both utility water and premise plumbing apparently contribute roughly equally to bottled water consumption.

The overall average probability of choosing bottled water as the primary source of drinking water at home is about 24% in the VOWS data. For someone who has strong trust in the safety of both utility water and premise plumbing, the probability of drinking bottled water is just 16%. That likelihood more than doubles to 37% for someone who strongly trusts utility water but strongly distrusts his premise plumbing. The likelihood of drinking bottled water skyrockets to 58% for a person who strongly distrusts both utility water and premise plumbing.

trustworthy tap?

As if it weren’t hard enough

All of this complicates things for water sector leaders trying to strengthen trust at the tap. We no longer have the luxury of ignoring what happens “on the other side of the meter.” Building trust and getting customers to kick the bottled water habit will need to include efforts to address concerns about premise plumbing. Efforts toward that goal are underway in lots of communities across the country; we need rigorous research to see what works and what doesn’t.

*Although trust in utility water and premise plumbing correlate positively, it’s not an especially strong relationship: the Pearson correlation between trust in utility water and premise plumbing is .514.

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