Water leaking from overflow valve on city water

Close the valves?

Are you suggesting that I close the valve to the fresh water tanks? My mistake but the water appears to be coming out if the overflow valves under the RV. I have two of them.

If you have a use/fill selector valve or similar, make sure it's fully in the correct position. The other possibility is a faulty check valve in the water pump that's allowing city water to leak back through the pump into the tank. The tank drains and vent/overflows sometimes share the same outlets or are very close to each other.

Valves under the rig are for draining the system. They should be in normal operation closed.

If I am using city water, why is the pump mentioned as a possibility of the reason the overflows are leaking water when on city water as I thought the pump is only used with fresh water tanks. Am I wrong?
Also, how does one shut the valves please as this has been suggested? I have a shut off valve that stops water going into the fresh water tanks but have never closed the overflow valves.

The pump has a check valve to keep water from going to the fresh water tank. It sounds like it is bad and allowing water into the fresh and out the drain. Fill the fresh tank and use the pump and no city water for this trip

Edit: the two valves you mention are probably the low point drains for both hot and cold. Close them.

From your description, I believe the valve you are talking about are the low point drains for the water system. In normal operation, they will be closed. Depending on the maker, they could be push-pull or quarter turn valves located somewhere above the point where you see the leak.
Try using the valve a couple of times quickly to clear the valve and see if your leak stops as debris may be preventing them from fully closing. Worst case may be to replace them.