I recently filled up the windscreen washer fluid, but yesterday found I had run out again. I refilled the reservoir today and noticed that I could see the level slowly dropping, but could not find any leaks and no puddles appeared underneath. I primed front and rear jets to expell any air and refilled the reservoir, but the same thing happened. I removed the pump and put my finger over the outlet which stopped the level going down any more. When I put the pump back in, the level started to drop again, so it must be draining somewhere along the line. However, the lines run up from the reservoir and without the pump running it should not be able to drain. Has anyone else experienced this and found a solution to the problem?