I have used Water-to-Go for a couple of years, particularly when I undertake a big expedition, and I must say, I cannot fault them! I have drunk water straight out of the Amazon River for 3 months using their bottles, as well as spending 9 months walking through in India topping up wherever I could find. Even the locals advised me against drinking water in some places, but I was confident that the Water-to-Go bottle would protect me. And I am pleased to say that I have returned without any water-based stomach issues! Plus, it helps save the planet as there are no single-use bottles flying about, and you save money too. Highly recommended!