Water pump running every 5 minutes

So....I arrive at the camping pitch this afternoon and start getting set up.  Fresh water tank:  filled, EHU:  connected, Gas: turned on, 12v main switch, turned on, Taps:  turned on and after a bit of spatter, water flowing.

Make a bacon sandwich and a cup of tea.  While eating, the water pump starts cycling ever 5 minutes!  What???  Scratching my head thinking....oh no....6 months of not using the motorhome and now I've got a water leak somewhere.

Decide to go outside and look underneath......steady drip of water coming down from the opposite side!!  Aarrgghhh!!  Go around to the other side....water is leaking out of the hot water heater drain plug.  Hmmmm.  I just put it back in before I left home and I'm sure I tightened it.  Maybe the O-ring failed.

Grab my big screwdriver and it turns a bit.  Water stopped leaking out.   Water pump no longer cycling.  Whew!!!!  Crisis averted.

Moral of the story:  hopefully no more lockdowns leaving the motorhome parked and not used.