Rendering Water Safe in Off Grid Conditions
Requires Knowledge, Skill, and Supplies
The main section on water the facts, your needs, common contaminants, the proper methods for treatment, filtration, purification, storage, and transport were all posted because in the end if you are to survive any period of time in a grid down situation without water from a reliable source you will need to consider all of those things.
Let me begin by telling you that the NSF (National Sanitary Foundation) which is a trade organization that touts itself as an objective oversight group setting industry standards for all things that come in contact with your food, water, or other basic needs that you ingest. I have interviewed a VP from the organization and was very disappointed to find that they are not forthcoming at all about the details of their "standards" or how the products are tested or certified. Unlike the UL who allows access to even the finest details of their criteria and testing methodologies, the NSF wants you to purchase the data via the IEEE. Why should you care? The answer is that the US EPA uses the NSF "standards" as the benchmark for their approvals of the safety of what you intake and advise you to only use items certified by them.
So here is how that applies to your challenge of purifying water for your survival off grid. The NSF standard is at best an outline. The NSF shockingly states its position as follows: "We do not certify, nor have a standard for portable / off grid filters or purification systems". I probed why to which this is their answer, "We have no way of knowing what is in the water therefore we cannot create a baseline to test the efficacy with". What I conclude from that is much more far reaching than just off grid purification; that says that the NSF is certifying "purification systems" as effective at purifying water which has already been rendered safe and potable.
Most people who have spent hard earned money on a Berkey Filter or other "popular" water purifiers believe that their "purification systems" will keep them safe in a grid down situation. Based upon a clear understanding of the need to know what toxins and biological risks are present, the need for specific filters for each threat, chemicals, treatments, dwell time and a long list of other factors that is clearly not possible. These systems are akin to snake oil.
The last thing that you want to do is save 15 pounds of water weight on a hike and end up two years later with a brain tumor or other form of cancer because you drank "filtered water" from a stream that had high levels of Benzene or Dioxin in it from runoff up stream.