Education setting manager Justine Munro said research proved poor diet was closely associated with low academic achievement, and schools that had gone water-free had seen improvements in behaviour, concentration and attendance.
Ms Munro said children also took the healthy drinking policy home, which helped influence parents to change their ways too.
Meanwhile, one Christchurch principal has made a splash in an effort to encourage other schools in the city to go water-only.
This afternoon West Spreydon School principal Marriene Langton let students tip a bucket of water over her head and spray her with water bottles.
The school has been water-only for 10 years and she hoped the stunt would raise awareness about the many benefits.