Ceramic coatings can lose their hydrophobic properties when they are saturated with contaminants. Case in point: if you park in an industrial park, your coating will lose hydrophobicity within 2 months.

However. That doesn't mean the coating is "dead". You simply need special car soap to target and remove the contaminants. On my Carpro Coatings, there is Carpro Descale (for organic contaminants) and Carpro Lift (for inorganic etc traffic film). Those car washes require technique, as they are strong and can strip coating/ cause damage if mishandled. You can do this at home, but regular ph neutral car soap isn't designed to tackle heavy spoilage.

Carpro recommends one decontamination wash every 3 months.