Fresh water system question

We just got back from our first trip with our new 2013 Rpod 177 and I have a question on the fresh water system. When we first got to our campsite, I hooked up the electricity and drinking water. On the second day, I wanted to check the gray water level so I used the monitor and checked all 3 tanks. I noticed that the freshwater tank was full and as I checked throughout the weekend, the level kept going down as we consumed water. My question is, (pardon the ignorance as this is the first travel trailer we have owned) once the fresh water tank is empty, does the pump automatically know to draw water from the city water outlet? Is there some switch over that has to be done?

Welcome to the forum.

Theoretically the pump shouldn't come on while hooked to city water, even if the power switch is turned on.  The pressure switch in the pump is set lower than most city water pressures.  Maybe the city water connection wasn't turned on at the campground's faucet?  Did you actually hear the water pump come on (you can't miss it)?

Note that you fill your fresh water tank from a different location than the "city water connection".  If I'm going camping where I know I'll have hookups I will only put a gallon or two in the fresh water tank for use while on the road (flush toilet, wash hands).  No reason to take 200 pounds of water with you if you don't need it.

good diagram

Just to throw some fuel to the fire; my dealer said that that the pump could be damaged if you used it while connected to city water.  He reiterated the point several times during the demo.  However the one way valves illustrated in bhamster post should eliminate that problem. 

I wil add .... Make sure that the campsite water is connected (threaded connection) to the input on the pod marked "city water connection." I've  seen folks just put the hose into the "fresh water" tank opening and think they were connectedthrough the city water port.