Despite California law requiring schools to provide free drinking water during mealtimes, a quarter of preteen or teenage students said they don’t have access to water at lunch, a new study reports.

Students who had access to free water during lunchtime consumed significantly more than those who didn’t, according to the research, published online Nov. 7 in the Journal of Adolescent Health.

Increased water consumption can help fight obesity, the UCLA researchers add.

“Water, which is non-caloric, may displace less healthy, caloric beverages, and is associated with reduced dental caries and improved cognitive functioning in children,” the study states. “Moreover, an analysis of a representative U.S. sample suggests that over half of youth aged 6-19 are not adequately hydrated.”

For the November study, researchers used data from the 2012 and 2013 California Health Interview Survey data, where 2,665 adolescents ages 12 to 17 reported whether they had access to free drinking water at lunchtime.

The participants reported that they drank an average of about five cups of water a day.

In both 2012 and 2013, 75.3 percent of students said their schools offered free water at lunch, mostly in the form of drinking fountains. Students of color were less likely to have access to water, the report found.

Students may drink more water if they have access to water in cups or bottles, the researchers added.

“Prior qualitative and quantitative research suggests that students may be reluctant to rely mainly on water fountains for water intake during the school day due to negative attitudes about water fountains,” the report states.