After the 40-minute deluge, the arena looked like a lake and the competition had to be delayed for a further hour while efforts were made to dry out the surface. At that stage, Germany were on target for a team gold despite a bad fall by their world champion, Franke Sloothaak. A cut on his right wrist required stitching.
The Netherlands, the 1992 gold medallists, have had a clear round from Jan Tops and the United States are in a strong position with a clear run from Anne Kursinski.
The British team, last to go of the 19 nations, had a disappointing start when Nick Skelton's Show Time put a foot in the water and then kicked out the back rail at the first part of the double - a massive triple bar with a two-metre spread - to finish his first round with eight faults.
Michael Whitaker then collected 16 faults on Two Step who, according to the team trainer Malcolm Pyrah, was "fazed" by the occasion. Whitaker had to use his whip coming into the big parallel at the second, but Two Step still hit the obstacle. He then knocked a brick out of the wall at seven, put a foot in the water and knocked down the last part of the double.
There was more gloom in the British camp when Geoff Billington, on It's Otto, became the third team member to fault at the water before going on to hit the last two jumps. He finished on 12 faults. The rainstorm arrived before John Whitaker's round could be started.
n The Appeal Committee of the international equestrian federation, the FEI, visited Pine Top Farm on Wednesday night to verify the German rider Matthias Baumann's evidence of alleged illegal training practices used there by the Argentinian team, who were competing on Wednesday.
The two photographs supplied by Baumann to back up his allegations show a wire strung 20cm above the top rail of a jump and another top pole with protruding nails. Neither photograph shows a horse or identifies the site.