It is recommended that you re-waterproof the exterior of waterproof clothing from time to time. Waterproofing is the first line of defence/protection for the upper material and strengthens the water-resistant properties of the material. Water beads off and this also means that dirt particles are also unable to remain on clothing. Waterproofing washes off and needs to be retreated. If you have time, check to see whether water is still beading off clothing, or whether it soaks into the upper material, which then grows darker.