It’s also going to have to stand being filled with water and possibly frozen solid in the winter. Kind of expect it might have something of an algae problem in the summer.
But you are correct that it will have to be an engineered structure. The expansion and contraction of the wall material will have to be considered due to seasonal temperature variations.
I would think that the tank may need a water recirculation pump and a heater to keep it from freezing in northern latitudes.
Another reason that a buried tank makes more sense. Bury your poly manufactured tank below the frost line and avoid these problems. In the end it is a lot cheaper.
Anyone who spent just a few minutes thinking about the practical problems with this idea quickly figures out that is just way too expensive to consider where there are other options.
Makes me think that the judges did not give the real world application of this idea much thought. But of course when you are judging a high school science fair perhaps that is not part the criteria for awarding the prize.
Real people have limited funds for such a project. Real world people make financial choices and choose the cheapest and most practical option. This idea just doesn’t fit the bill.