The water repellency longevity is dependant upon driving conditions and the number of times the filter is cleaned. Generally speaking, we recommend changing the Pre-Filter every 6-12 months. However, a quick test can determine if it is time to change your Pre-Filter. Simply take an ordinary clean spray bottle filled with water and gently spray the Pre-Filter. If the water beads off the Pre-Filter, your water repellency is still working. If you see water enter through the Pre-Filter, it is time to purchase a new Pre-Filter.
Water repellency feature will last 6-12 months depending on driving conditions and number of cleanings