Water Purification Basics: a few questions before I begin

I have been asked to do a compare-and-contrast covering the various methods of water treatment available for preppers. Having spent 18 years operating a waste water treatment plant (the same technology as drinking water treatment, just with looser standards), I'm the closest we have to an expert on the subject so I'll give it a shot. This will be just an introduction to water treatment, with more details in future articles. This is a very important subject and I don't want to leave out information, but I also don't want to write a ten page article that nobody is going to finish reading. 

Before getting into specific methods or brands of treatment I need to ask a few questions. All of these will come into play when you start looking at filters and other treatment methods.

1. How clean do you want/need your water? I have worked in labs that required water so pure it would dissolve copper tubing, and I spent many years discharging treated water into a major river that was dirtier than what I was putting into it. Some uses may not require water as clean as others, I'm pretty sure your dog (who drinks out of the toilet and stray mud puddles) doesn't need water treated to the same standards as you'd use for mixing baby formula. The EPA and WHO have established drinking water quality standards, technical data that I'll try to put into layman's language.
   
   Also, not all raw water needs to be treated. Rain water and melted snow would be safe to drink in all cases, unless you're dealing with chemical or nuclear fallout. I grew up drinking water straight from a (fairly deep) well and have never had any issues with it. You can also develop a resistance or immunity to any local microbes that don't immediately kill you, but changing location will change the definition of “local” and you may run into problems until your body adjusts (Montezuma's Revenge).

2. What's in the water that you need to remove? Unless you have some idea of what you're trying to remove, you'll be lucky to pick the right method of getting it out of your water. A filter that will remove giardia cysts may not be good enough if you're dealing with chemical contaminates. Even without access to a microbiology/chemistry lab, you can do some research before a crisis to get an idea of what to expect. This is where things get personal, because there are too many possibilities for me to list them all. You'll need to think about where you may be when you need a water treatment system and do the research now.

3. How much water per day are you treating? The standard is one gallon per person per day for drinking and cooking purposes, but what about cleaning your body and clothes? Does your water system need to be cleaned periodically? For how many people are you prepping? Larger demands are going to require larger systems to clean your water or multiple smaller ones.

4. How long are you going to be treating your water? It's just common sense that a pocket filter might get you through a weekend in Mexico, but it isn't likely to last for several years' worth of daily use. Be wary of the claims made by manufacturers, unless you've thoroughly checked their system out. The filter that you pick for your BOB may be different than what you'll want to use once you get to your safe location, or you may only need to treat your water until the city gets their plants back online and the pipes flushed. Different needs for different plans.

5. Are you prepared for when your water purification system fails? Nothing lasts forever, so having a back-up plan is essential. It may be as simple as just drinking untreated water for a short period and dealing with the consequences (that weekend in Mexico), or it may be as complex as making another treatment system, but you need to be thinking of redundancy. A good idea for a fixed location would be to store your treated water and rotate through your stocks. That way, when the filter fails, you'll have a buffer supply to give you time to repair it or get another system online.

6. Are you aware of the indications for when your purification system fails? Do you have a way to test your system and the materials and skills to run those tests? One of the first filters I bought for hiking and camping came with a bottle of blue dye. The instructions were to add a few drops of the dye to some water and run it through the filter. If the dye passed through the filter it was a sign that it had failed. I'll get into specifics for each type of system as I cover them, but you need to be aware that there are simple ways to test water systems and you need to be able to run those tests.

7. Are you aware of how important maintenance and hygiene are going to be? Some filters require an occasional backwash to flush them clean while others require boiling or chemical cleaning and others just need to be replaced. Be prepared and learn your system before you need it. Make sure everyone who may need to use it is also trained.
   
   Hygiene is an absolute must-have in any crisis situation. Sharing a water bottle with another person is also sharing their diseases. Unless you're comfortable sharing bodily fluids with someone, get them their own bottle. Keeping your water treatment equipment clean will avoid cross contamination. Think about it: if your hands are filthy, do you really want to touch anything that is going into your mouth? It would be wise to pad the numbers in your answer to number 3, above, to allow for some surplus water for hygiene purposes.

Those questions should give you something to think about, and maybe form a few questions of your own. I'll discuss the different methods of water treatment and some of the various types of equipment in the next few articles. If you have questions you would like to see answered here, feel free to leave comments and I will do what I can to find an answer.