Former trustee and senior kaiako Hori Chapman said encouraging tamariki to drink water at the kura was "the norm".
"Drinking water is part of accelerated learning and maintaining good levels of hydration, so the policy is critically important," he said.
Implementing a water-only policy was connected to supporting whanau to make good eating choices, acknowledging that there could often be a conflict between the behaviours promoted at the kura and those normalised in the home.
Students agreed that drinking water was the healthiest choice when presented with options.
"Fizzy drink is really really bad because it makes you fat and gives you lots of calories," student Asher Williams said.
"We're technically only allowed to drink water or milk here anyway. It's not as if fizzy comes out of the taps," Ty Pomare said.
The government push for water-only schoolgrounds aligns with the kura's recent movements to further promote the health of its students. Earlier this year the kura began to offer the Real Kai service - a low-cost food delivery service that maximises locally grown, seasonal produce - which had been a hit with whanau.
Te Taitokerau Iwi CE spokesperson and Te Runanga o Te Rarawa chief executive Kevin Robinson said the battle for sugar-free drinks was being won when mokopuna asked for inu wai as their first choice.
"We've beaten it when the day comes that we can have a can of fizzy in the fridge, and in six months' time it's still sitting there," he said.