What are these water meter cables?

[GamerGry123]

It looks like grounding because it is 1 cable and from grounding the cable is that color. I thought that the owner of the apartment could remotely check how much water they use and the meters are connected to electricity. But I don't know.These meter cables are in the bathroom but not in the kitchen.

[Levent]

Electrical grounds. So that you won’t get shocked when you turn the faucet on. Those are mechanical meters by the way. 

[GamerGry123]

11 minutes ago, Levent said:

Podstawy elektryczne. Abyś nie doznał szoku, gdy odkręcisz kran. Nawiasem mówiąc, są to liczniki mechaniczne. 

But through the wall they measure how much water i use. Some device and then he gets a bill how much to pay.

[mariushm]

It's possible it has a super capacitor or battery that charges from the water flow, just enough to send a few packets of data over the air to the reader. Some meters have a non rechargeable battery that's high enough capacity to last for 10+ years.

 

Or the reader on the other side sends some pulses of energy through the wall, just enough to charge the IC and have the IC report back through the air the reading, basically a few ms of wireless transmission.  Sort of like RFID on price labels or whatever, the RFID tag has a small coil of wire which picks up RF and converts that to energy, and then the chip uses that energy to send the data over the air using same coil as antenna.