Inclusion of the term "IoT" was deliberate, monitoring water (distribution, use, misuse, quality) remotely and at a scale precisely is the problem that IoT can solve.

There's no "IoT" problem here. You can have plenty of automated systems monitoring your infrastructure without the security nightmare of making them accessible on the public internet.

I don't think that IoT implies publicly accessible (correct me if I'm wrong). "IoT" smart water meters exist, and they usually use cellphone networks to send data (water usage) to the utility company.

The "I" in "IoT" stands for "internet". If the only thing "IoT" means is 'small digital sensors', then I'd suggest it's a meaningless buzzword.

The Internet of things (IoT) is the network of devices such as vehicles, and home appliances that contain electronics, software, sensors, actuators, and connectivity which allows these things to connect, interact and exchange data.

https://en.wikipedia.org/wiki/Internet_of_things