Caravan cover

I have had my 3rd Protec caravan cover for 17 months and always make sure my van is clean and dry before covering it , I always cover my van when not in use .

Recently when removing the cover I noticed the van was wet !

I have  spoken to Protec and the suggest I wash the cover as the breathable pores must be blocked and that I use a non detergent cleaner and recommend its washed once a year , washing it this time of year not practical however looks like I have no choice .

Has anybody else had this with there breathable cover and what non detergent should I use ?

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