The gendered relationship between income and bottled water consumption

Bottled water was something of a novelty in the U.S. back in the 1990s when I started working in the water sector. It was perceived as a weird kind of luxury good, purchased mainly for convenience and taste by people who perhaps had too much discretionary income. After all, bottled water is lightly regulated and orders of magnitude more expensive compared with tap water.  

Thirty years later we know better: vast empirical research* shows that, counterintuitively, bottled water consumption in inversely correlated with income in the United States. It’s now well-established that bottled water consumption in the U.S. is greatest among the poor and working class. In The Profits of Distrust, Samantha Zuhlke, David Switzer and I link the surprising relationship between income and bottled water consumption to distrust of institutions generally, and distrust of tap water in particular.

A project about risk perception I’ve been working on lately got me thinking about bottled water in new and different ways. And I stumbled on something remarkable: the relationship between income and bottled water consumption in America is distinctly gendered.

Gender and risk aversion

I wondered: does a gendered pattern of consumer behavior apply to drinking water? In the past I’ve noted that, compared with men, women tend to express concern over water issues. Since bottled water consumption is strongly linked to distrust of tap water, women’s greater risk aversion might drive them to the bottle—especially for the most economically vulnerable. Is the inverse relationship between household income and bottled water consumption really about women?

To the data!

Using data from three independent national surveys, I fitted statistical models that estimate the likelihood that a person uses bottled water as his/her primary source of drinking water at home as a function of income and gender, while adjusting for other factors that often correlate with drinking water choices (like race, ethnicity, age, and education). That’s a standard approach to analyzing consumer behavior. But then I adjusted the models to see whether the relationship between income and bottled water consumption varies for men and women.**

This graph shows the likelihood that a person drinks bottled water at home by income. The red line represents that likelihood for women, the blue line the likelihood for men. As we’d expect from past research, both lines slope downward, indicating that bottled water consumption decreases as household income increases. But crucially, the line is higher and steeper sloping for women than for men. For people whose annual household incomes are below $30,000, women are about 10% more likely than men to drink bottled water. That gender gap shrinks to about 5% when income reaches $60,000-70,000. At incomes above $75,000 the gender gap becomes statistically insignificant.

The Verasight results are even more stark. There is effectively no correlation between income and bottled water consumption for men, but a steep, negative correlation for women. A woman whose household income is below $15,000 has a 52% chance of drinking bottled water at home—a more than 11% higher likelihood than a man of comparable income. 

What it all means

Bottled water is a profoundly regressive “luxury” good, since it’s consumed mainly by lower-income Americans. Women are disproportionately responsible for household consumer decisions, particularly when it comes to food and health-related purchases, and their decisions are rational. If low-income women’s risk aversion drives them to bottled water due to distrust of the tap, then overcoming America’s bottled water problem starts with poor and working-class women. Utilities must find ways to communicate their quality and illuminate the problems with bottled water in ways that resonate with lower-income women.

But no public relations campaign alone will ever be enough to (re)build trust if the poor continue to experience water service problems disproportionately. Winning women’s trust requires a commitment by the entire water sector—utility leaders, regulators, advocacy organizations, and researchers like me—to ensure that tap water is truly excellent for everyone, everywhere, and always.

*See this study, this study, this study, this study, this study, and many more.

**In statistics this procedure is called an interaction.