A MISSING leaf protection grill and lack of an overflow warning system caused the Princess Diana memorial fountain to flood last week.
Owner Royal Parks blamed 'exceptionally high winds' which caused leaves to fall and block the fountain outflow before the equipment had been installed.
The flooding occurred a day after the water feature was officially opened by the Queen in London's Hyde Park.
'Exceptionally high winds stripped trees of their leaves which were then caught in the outflow of the fountain, ' said a Royal Parks spokesman.
He added that a grill to prevent leaves entering the pipework system would be installed as soon as possible but that staff would have to pick leaves from the fountain in the meantime.
The memorial, designed by consultant Arup and built by contractor Geoffrey Osborne, consists of a granite channel forming an oval on sloping ground.
Water flows downhill in two directions from an outlet where it is pumped into the channel.
It then flows into a 'tranquil pool', where it is released into the Serpentine lake.
But the water level meter which would detect overflow in the pool and trigger a switch to turn off the pump was not due to be installed until August.
'We wanted to see how people reacted to the pool before we put it in, ' said the spokesman.
Water for the fountain is sourced from a chalk aquifer 150m below ground level via a well. An Arup designed pumping system circulates water around the feature.
Pumps were slowed down last week when the pool flooded.