Hi,
Suggest you first stop rainwater getting into your fuel tank as E10 does not "pull" water from the air.
Second, repair the damage the water has caused.
Third, add Ethanol to your fuel tank to enable any water in the tank to be removed.
You could add "Dry Fuel", but ethanol or E10 is cheaper.
Does that make sense to you?
Cheers,
Iain.