Student-level data
dehydration
DEHYDRATION, REGRESSION
Table 
Combined table of student-level dataStudents who received the BI demonstrated several positive changes from baseline to follow-up. There were several statistically significant changes in their knowledge regarding the effects of SSB, which appeared to translate to an increase in water bottle carrying behaviour, with 82 % reporting they bought a water bottle to school post-intervention compared with 76 % at baseline (Students who received the environmental intervention only or the BI only showed a very similar pattern of results. They also had several statistically significant changes in their knowledge regarding the effects of SSB and showed changes in their bottle carrying behaviour (74·06 % pre; 78·25 % post; Students receiving both interventions showed statistically significant changes in their knowledge regarding the effects of SSB, and like the other groups, they increased their water bottler carrying behaviour. Students in this group, however, were also statistically more likely to fill up their water bottle at school (75·23 % pre; 86·22 % post; Whilst group 4 results suggested some change (in a positive direction) in knowledge about the effects of dehydration, there was a statistically significant decrease in the proportion of students correctly identifying that SSB have no nutritional value, as well as a change in bubbler usage and decrease in daily SSB consumption.There were decreases in the proportion of students reporting that they used the existing school bubblers (unchilled). However, this was only statistically significant for the schools receiving the combined intervention as well as control schools. There was an impact of COVID-19 as students were directed not to use the school bubblers and, in some schools, these were switched off, due to concerns about COVID-19 transmission.From baseline to follow-up, the control group had less loss to follow-up for the student surveys than any of the intervention groups. This may be due to the control group having fewer year 7 students overall than any of the intervention groups, meaning that fewer year 7 PDHPE classes in these control schools, making the follow-up surveys easier to conduct. The control group also had a greater number of private schools and a higher Index of Community Socio-Educational Advantage (ISCEA) score for schools within the group compared with schools within the intervention groups. Group 1 had the greatest loss to follow-up, which could be related to the fact that this group had two schools that were either remote or outer regional, which may have affected connectivity to the internet. At one of the schools a teacher estimated that less than 50 % of students would have internet access, which would have impacted students’ ability to complete the survey if they had not done so before commencing home schooling due to COVID-19.Whilst across all intervention groups, there was an increase in the proportion of students reporting drinking one cup or more of water daily at follow-up, this was only significant for the environmental intervention group and interestingly the control group. The proportion of students reporting SSB consumption of one cup or more daily decreased across all groups and was statistically significant.To further examine changes and individual and joint effects of the interventions, multivariable ordinal logistic regression models were derived for each outcome (Table 
Individual and joint intervention effects on the weekly consumption of water and SSB between baseline and follow-up