I’d just like to add a couple of things to Whale’s excellent reply.
Firstly, I’m assuming that apart from the water situation, you like living in the apartments, otherwise I would be recommending that you find somewhere else and give them notice that you are leaving due to a failure to provided the basic amenities of the rental unit.
Otherwise, how about spicing things up by threatening to move into a hotel at their expense until such times as they force the owners corp to fix the hot water.
You probably cdo that without prior permission but they need to be reminded at maintenance of common property is not optional – the Owners Corp is legally obliged to fix the hot water (Section 62 of the Strata Schemes Management Act) and the owner should be pressing them to do exactly that.
Or you could seek an order through Fair Trading, forcing the owner to seek a Section 62 order. It’s not going to happen overnight but if the strata manager tells the Owners Corp that they don’t have any choice in the matter could get the ball rolling before winter sets in …brrrr!