I bought the filter water bottle to use whilst on a 3 day wild camping trip in the Highlands. The first time I tried using it, there were visible black specks in the filtered water. I assumed these were already present in the bottle I was filling, but after rinsing and repeating 3 times, they were still present. I tried my friend's bottle (same brand, same model) and there were no specks. I tried mine again and there were again visible particles in the water. I assume I had a dud, but I lost confidence in the filter and decided not to use it again. It went in the bin when I got home. If I need a filter again I will not be buying a Lifestraw.