Never just use water, I am pretty anal when it comes to looking after the RS.
Having just had coolant pump changed, wonder if the water bottle has been damaged although it’s on the opposite side of the engine, already booked in to dealer for investigation.
When replacing the water pump, the whole motor shall be moved to other side by hanging on wings (that is why 2 days for work), so there is possibility for damage.No need to mess with the wing / inner wing on that side when replacing the water pump.