Your waterproof footwear could be soaking up water just because it is dirty. Through use, the outer surface of footwear will pick up contaminants, such as dirt, which attract water. This masks the effect of any Durable Water Repellent (DWR) coating, leading to footwear 'wetting out' in wet or damp conditions.
Cleaning waterproof footwear with Nikwax Footwear Cleaning Gel™ will not only remove contaminants, such as dirt, but also revitalise DWR, causing water to bead on the outer surface once more. Once the footwear has been thoroughly worn, you will need to add DWR, using Nikwax Fabric Leather Proof™, after cleaning first with Nikwax Footwear Cleaning Gel™.