A study on the effects of Berkeley’s soda tax found that the tax has discouraged residents from purchasing sugar-sweetened beverages, but it hasn’t negatively impacted the local businesses that sell it.

Researchers found that though sales of sugar-sweetened beverages have decreased since the tax was implemented, the drop was offset by increased sales of water and other beverages. As a result, Berkeley saw little difference in the amounts of revenue stores took in and the amounts consumers paid for groceries compared to other cities.

The study was funded in part by a grant from Bloomberg Philanthropies and published Tuesday in the research journal PLOS Medicine. It was conducted by researchers from the University of North Carolina’s Gillings School of Global Public Health and the Oakland-based Public Health Institute.

Researchers collected and analyzed several sources of data from before and after the tax took effect, including beverage prices, store revenues and surveys of Berkeley residents.

According to co-first author Shu Wen Ng, the UNC team didn’t quite know what to expect from the study, though they had previously studied the effects of national soda taxes in Mexico. Berkeley’s relatively high income and education levels, as well as its status as the first American city to implement a soda tax, made it an unpredictable case to study, Ng said.

The study found that sugary beverage sales declined by nearly 10 percent in Berkeley stores after the tax took effect, while other drinks gained popularity. Sales of water increased by about 16 percent.

Co-author Barry Popkin said given that sugary beverages are primarily purchased by lower-income consumers, the fact that the soda tax was so effective in decreasing soda consumption in a economically well-off city like Berkeley suggests there will be an even greater impact in cities with higher low-income populations.

”I was surprised,” Popkin said. “It speaks very well for the health impact … in areas with high low-income populations.”

In an emailed statement about the study, the American Beverage Association, which represents Coca-Cola, Pepsi and other soda producers, asserted that Berkeley, because of its demographics, makes a poor example of how soda taxes usually affect a city. The statement also noted that the beverage industry has taken voluntary efforts to offer more consumer choice and fund information campaigns nationwide to improve public health.

The organization has long opposed the soda tax, to the point of spending more than $1 million in campaign funds against it before Berkeley residents approved the tax via the Measure D referendum in 2014.

For co-first author Lynn Silver of the Public Health Institute, the results proved the tax’s effectiveness.

”Overall, the tax was a home run,” Silver said. “It did what it said it was gonna do.”