You do NOT need to have power or WiFi near your water meter. The water sensor device that straps on to your meter is battery powered. It uses a specialized battery that will give it significant life.
The water sensor device (on your meter) communicates to a bridge device via RF (Radio Frequency) which can be located anywhere in your home. This bridge device (in your home) must be connected to power and must be able to access your WiFi network.
As a general rule, your water meter should be less than 1000 feet away from the bridge device in your home.