I was washing my car today and I realised that I now there's condensation in my headlamp. How do I fix this?

 

Take out your bulb, use a hair dryer to clear the condensation, then put your bulb back in making sure you have a tight seal.

Also check the rubber hoses (they are 'U' shaped), make sure they are angled down to prevent water and moisture from entering the hose into the headlight. These hoses allow hot air created by the bulb to escape will preventing water from entering.

 

you could always drill a drain hole as well. My headlamps have one because of the HID lamps i installed...I have never seen any condensation build up from it.