For your first AG batch I would not worry about changing your water unless it tastes bad to drink out of the tap. I would go with it. If you have a charcoal filter it could help with taste but wont really affect it for brewing purposes. Not necessary however, if it tastes good straight from the tap.
You MIGHT want to use some pH 5.2 to help buffer the water so that you efficiency does not suffer if the residual alkalinity of your water does not agree with the beer you are making. This again is not a huge deal and I personally would not worry about it for my first AG batch.