If the water is under driver side, the major culprits for such leakage of water are the brake servo top fixing bolts, the radio antenna and in some cases floor rubbers.
1. In case the servo is causing leakage, make sure the holes of servo bolts are covered with rubber seals of size 1.
2. In case of radio antenna, Remove the antenna and apply silicone around the hole and then re-fit the antena.
3. In case of floor rubbers, put rubber seals of size 3 in the mising areas.
If the water is under passenger side, the main culprits are vacuum bottle housing fitting and , floor rubber seals and AC water drainage(offcourse this is not dependent on rain).
1. For vacuum bottle housing, remove the housing, that is under black shield of blower motor. Put some silicone on the border areas and re-fit the housing.
2. For floor rubber seals, do as mentioned in point 3 above.
3. For AC water drainage, consult AC mechanic.