We have a new(bought in April), 2014 Winnebago Sightseer 35G. I've begun getting a water drip from under the coach when hooked to city water. I use a regulator. Depending on how level the coach is, ...
How full is your fresh water tank? Is it overflowing?
Hooked to city water...... If you have a 'water panel' with switches/valves check that 'fill' switch/valve is fully closed. If leaks thru goes directly to fresh water tank
Also...water pump internal check valve can leak....allows city water to backflow thru pump to fresh water tank.
IF fresh water tank is FULL turn off city water and use pump. That can clear pump internals and may be check valve will close properly