No. Sonic can run on mains power (a power supply is included) or lithium-ion batteries (4 x AA). Lithium-ion batteries on average last for about 18 months (depending on water usage).
If you're running Sonic on mains power and there is a power failure, Sonic will automatically use the battery as a backup.
Having said that, Signal does require mains power, but it can be situated almost anywhere in the property and doesn’t need to be near water mains.