I understand the water maybe, but why would they require permanent heating? I know the answer, but these local and state authorities need to be watched for overreaching just as much as the federal government.
Without permanent heating, pipes can burst and cause all kinds of other damage, including eroding the ground so that neighbor's homes start to sink, or big old trees start to topple, possibly bringing down power lines or breaking someone else's underground gas lines. So they pass a one-size-fits-all commonsense basic requirement. Most building codes have some sort of rationale. The assumption here is that almost no one would want to live in a house without running water. In this case, while they may be carrying in drinking and wash water, how are they flushing the toilet? I imagine conditions are a lot worse if you would see or smell them in person than how they sound in print.
Obviously this family needs some help. I hope the publication of the story brings some help alongside.