My 3yrs old girl go to preschool. And she seldom drink water so cause her constipation. Any solution ?

Usually in preschool the kids will drink their water due to peer pressure, the teachers may need some coaxing. Or u may Replaced with diluted Ribena,glucose water？though not good to keep drinking sweet drinks but better den none.give her more fruits like prunes , kiwi, banana etc which provides fibre. Play games with her to trick her into drinking plain water at home eg, who can fin a cup of water first n reward her if she wins? Or play patient n dr n give her some water in syringes