I read a lot of survival and preparedness articles that refer to purifying water. I just want to clarify some of the terminology surrounding the treatment of water. First off I dislike the term purifying, it is a marketing word that hopes to make you think the water is now pure. No product or process can remove 100% of the contaminants from the water every single time. That is why you see 99% to 99.99999% attached to them.
I much prefer the term treatment as that is ultimately what happens.
We take contaminated (as a water treatment professional I assume all water to be contaminated with at the very least bacteria) and treat it until it is safe to drink. Many volumes of books can and have been written on water treatment and we could spend the rest of a lifetime going over them all, way beyond the scope of a simple blog entry. So I will keep it simple the very basic steps are settling, filtration and disinfection. There are other and different methods which I hope to cover later.
Settling is just taking the water and letting it get very still and all the sediment that can fall to the bottom reach the bottom. Settling makes the other treatment steps easier, as the loading will be reduced.
Filtration, is the physical removal of contaminants from the water through a straining process. When it comes to filtration the finer the filter the better. A sock is better than not filtering, a sand filter is better than a sock and a nanometer filter is better than sand. Chemically assisted filtration is also very common and is something I will cover later.
Disinfection is the removal, killing or inactivation of the pathogenic (disease causing) organisms. Inactivation is stopping the organism from reproducing inside your body and causing disease (but they stay alive). Disinfection is achieved normally through chemicals like chlorine, and through ultraviolet radiation. There are other chemicals which will be covered (you guessed it) in another post later.
At this point you may be wondering why I have ignored boiling and distillation. Boiling is technically sterilization, not disinfection. Sterilization is the killing of all the organisms where as disinfection leaves some of them alive but not a danger. This is a minor difference but in my opinion a critical one.
Distillation is capturing the cooled water vapor after it has been boiled. Distillation can remove too much from the water depending on what you need the water for, best example of this is calcium carbonate and other dissolved minerals like iron. Calcium and iron are good for us and shouldn’t be removed from drinking water.
Water that I plan on drinking will hopefully go through all these steps (except distillation) as each step helps in different ways. I hope this helps you understand with some more clarity the basic steps of treating water and if I am really lucky I have converted away from the word “purifying”.