Water pump sending water overboard

[Schoolhouse]

We have a “new to us” 2014 Winnebago View 24V. When running the water pump to fill the toilet or wash hands I discovered that the water levels were dropping rapidly. I discovered that any time the pump runs it also dumps water out, what appears to be, either the fresh water tank drain line, or the over flow line. I have checked all of the valve levers I am aware of and all appears normal. Looking for hints of what I missed. I’m assuming it’s a Newbie mistake but I’m at a loss. Suggestions? Thanks in advance!

[VI Roamers]

If you are connected to outside water it's completely different than if you are using your water pump to fill your toilet or wash your hands.

I have to assume you are not connected to an outside tap, so it cannot be your fresh water tank drain or it would all be gone. So, I am betting you have a hot and a cold water system drain valve. Both are low points in their respective systems. The water pumps uphill into the pipe system from the cold tank, then it fills up either the hot or the cold water lines. There is two drains... figure out where they come from then look into your rig on the inside to find the drain valves.

[powercat_ras]

Yes you have a low point drain valve that is partially open.

[Schoolhouse]

The low point water valve was the culprit. You made the call! All seems good. Thank you all for your quick response!