The takeoff distance on a
wet runway is the greater of the following values:
•
TODdry = Takeoff distance on a dry runway
•
TODN-1 wet = Distance covered from brake release to a point at which the
aircraft is at 15 feet above the takeoff surface, ensuring the V2 speed to
be achieved before the airplane is 35 feet above the takeoff surface,
assuming failure of the critical engine at VEF and recognized at V1.
the above is from airbus hope it helps