Mr Greupink said the partnership with Glenholme School (a decile 3 school) worked with the Board of Trustees not charging him to hire the pool and covering the associated costs, while he offered lessons to students for just $5 each - to cover staff costs.
The trial started this term with very little advertising and already has 40 children enrolled.
"We are doing it to look after the community, to look after the school. It's a long-term investment."
Mr Greupink said he would love to do similar in other schools.
"People talk the talk, you've got to walk the walk."
Mr Greupink said the programme aimed to give children the ability to swim for survival as well as raise water safety awareness such as the dangers of swimming in baggy clothing.
Glenholme School principal Nancy Macfarlane said a study last year showed pupils were quite confident swimmers but the school wanted to continue to improve that to keep them safe around water.