What would the law be, hypothetically, if the water meter had an incandescent bulb that lights up when water passes through it, or some other Torah-level prohibition?

After all, nowadays there are outdoor lights at private homes that turn on when people pass nearby, and I haven’t seen people being careful to avoid walking near such lights (some of them may be lit by an incandescent filament).

Regarding lights that turn on because someone walks past them, Rabbi Wosner (in responsa Shevet HaLevi) and others already wrote that this is permitted. But there, the reason is that whoever installed the light did so for his own purposes, and I am just passing by; he cannot forbid me from walking through the public domain. In my humble opinion, there it is not even a case of unintentional action, but at most mere involvement without intent. I am not doing both things, only walking, and the light turns on by itself. But in our case, he is consciously activating both things (like dragging a bench and making a furrow), and furthermore it was put there because of him (as a condition for using the water).