Hi MrMulder 🙂 Thanks for the tip. I’ve searched online and there are quite a few of these systems available from various brands. I think that lifestraw is fitted with membranes containing larger pores – microfiltration- that’s why you can use your mouth directly to suck the water out of the bottle, however, these membranes don’t remove viruses which can also cause diarrhea. I’ll get in touch with them!