Fresh water

Make and model will help get answers. I would say most, if not all, motorhomes will have valves in the wet compartment to control flow of fresh water. Typically, one would close valve to onboard water tank and this now opens city water connection to flow water into camper.

Is your pump on? In all the campers I've owned, if you turn on the pump the water will come from the tank. If not, it comes from the city water.

Is your water pump coming on?

My Itasca Spirit does not require a manual valve closure. Attachment or disconnect of the city water pressure automatically adjusts the valve.

It is a Holiday Rambler Vesta, did not have the pump on. First night out we were self contained all seemed good, second night connected to city water all seemed good, last night had no pressure in shower saw that tank was empty. I thought once connected that the pressure would have us using city water.
I took the regulator off the hose seems ok but not sure if we are on city or fresh tank

I really think the opposite is true, of what a previous poster stated regarding opening and closing a valve. I believe that in most motorhomes, once you are connected to city water and have the water turned on, it is automatic, without the need for turning any valves. Make sure there is no obstruction of a filter on the inlet side of the motorhome. What is curious, is why, if you had the water pump off, the tank would empty. There is no way that the water would flow without the pump being on, at least in my opinion. Did water flow past the regulator? Try it without the regulator.

MAC 82 wrote:
It is a Holiday Rambler Vesta, did not have the pump on. First night out we were self contained all seemed good, second night connected to city water all seemed good, last night had no pressure in shower saw that tank was empty. I thought once connected that the pressure would have us using city water.
I took the regulator off the hose seems ok but not sure if we are on city or fresh tank

If self contained, then you had to have the pump on to draw water from fresh water tank.

If on city water and pump is not on, then you should not be drawing from the freshwater tank. I think your pump is on and you are completely pulling from the freshwater tank.

Pump was on the first nite, not on now pressure is ok.
If the pump switch is on will the pump continue to run or shut off when not running water?

It will depend on the water pressure and your regulator. If the city water pressure is lower than your pump then your pump will try and pump up to its shut off setting. Though this has only happened once to me because city pressure is usually much higher than the pump switch. You said that your pump was off though so I would start looking for a leak somewhere. Even a fast drip will drain many gallons over several days.

Thank you all I will continue to monitor and work this out