AND, not only turn the power off, but turn the water off. If you have
a major leak when you are gone, it can be pretty nasty.

I had a couple of summer places once, and in the winter, not only did
I turn the power and water off, but also drained the tank. However,
make sure to fill the tank FIRST before you turn the power back on!
The elements will burn out otherwise, as then MUST be immersed in
water when powered up.

I had to explain to the intellectually challenged person who bought a
house from me that they really needed to turn the water off when they
were out-of-town for more than a couple of days.