Does this unit plug into a standard 120 volt outlet?
Do you have space in the panel for a 20 amp breaker?
If so, it is feasable; You will need to run #12 Romex and wire it in to an outlet that is rated for 20 amps. When you buy the outlet, make sure
it is rated for 20 amps;
the most common outlets are rated for 15 amps.
If you have an air conditioner and it is running when your water heater kicks in, it may exceed the 30 amps limit. Or if you are running an electric space heater, they are usually around 1500
watts or 12 amps. For that matter any high wattage appliance will get you close to your limit of 30 amps when the water heater kicks in. Those would be areas of concern.