To examine the relationship between knowledge and beverage consumption habits among children.

Cross-sectional analysis. Linear regression was used to identify sociodemographic, dietary and behavioural determinants of beverage consumption and knowledge, and to describe the relationships between children’s knowledge and water and sugar-sweetened beverage (SSB) consumption.

Seventeen elementary schools in London, Ontario, Canada.

A total of 1049 children aged 8–14 years.

Knowledge scores were low overall. Children with higher knowledge scores consumed significantly fewer SSB (β = −0·33; 95 % CI −0·49, −0·18; P < 0·0001) and significantly more water (β = 0·34; 95 % CI 0·16, 0·52; P = 0·0002). More frequent refillable water bottle use, lower junk food consumption, lower fruit and vegetable consumption, female sex, higher parental education, two-parent households and not participating in a milk programme were associated with a higher water consumption. Male sex, higher junk food consumption, single-parent households, lower parental education, participating in a milk programme, less frequent refillable water bottle use and permission to leave school grounds at lunchtime were associated with a higher SSB consumption. Water was the most frequently consumed beverage; however, 79 % of respondents reported consuming an SSB at least once daily and 50 % reported consuming an SSB three or more times daily.

Elementary-school children have relatively low nutrition and water knowledge and consume high proportions of SSB. Higher knowledge is associated with increased water consumption and reduced SSB consumption. Interventions to increase knowledge may be effective at improving children’s beverage consumption habits.