The main advantage to filling your fresh water tank is that you save money, electricity and you can be off-grid. The disadvantage is that it requires you to physically fill the tank (which can be a chore in cold weather).
Option 2: Heat/Insulate Your Fresh Water Hookup
If you are parked in an area where city water is available, you can bypass your fresh water tank and directly hookup to a water spigot. This means your fresh water hose will be constantly exposed to cold weather elements, so you’ll need to protect it (and the spigot) from freezing.
Brittany Yunker uses a heated hose & insulated spigot for fresh water during the winter months
Purchase a heated drinking water hose. This hose will require constant electricity and will replace your normal potable water hose. Next, it’s a good idea to insulate your spigot by wrapping it with foam insulation. You can also wrap your heated hose around your spigot to ensure it doesn’t freeze.
The main advantage to heating and insulating your fresh water hookup is that you won’t ever need to fill your tank or use your water pump (pressure will come from the city water). The disadvantage is that a heated hose can be expensive, will require electricity, and you will have to store/transport it during the warmer months.