The life straw cost in the vicinity of $38 from outlets like BCF BUT read the fine print on how to use the life straw before you decide on buying one. I bought one then read the internal instruction sheet , do not use with saline water as it will affect the chemicals used so i guess that drinking water from a creek would be ok but a puddle that might contain ground salt , there is no positive answer, but if the water source is saline / salty like from the ocean then it may not suit the purpose, our urine is saline so its not meant for that, I bought one , then got to read the fine print, would not have bought it knowing the limitations, it sits in by survival kit. I carry spare water in 1.25 or 2 litre bottles , takes up the spaces between my gear and I know it comes from a safe place .