We recently received an email from a reader who is just beginning his journey into emergency preparedness. He had a question about water distillation, and how it can be accomplished in the backcountry. So, we took the opportunity to provide some context on where it falls in the list of water purification options, and explain some of its advantages and disadvantages.

See below for the original email, followed by our response:

Good morning. Straight off, I admit I am new to prepping. I'm trying to understand the equipment needed to produce (not just boil, but distill) raw water into potable water. However, all the prepper-recommended sites/equipment (which I've found so far) offer systems that have a power cord to be plugged into a 110v receptacle. I must be missing something. If I am in a situation where I am having to clean my own water, I'm pretty sure there's not going to be any operating electrical sockets. Is there not distillation equipment designed for use in the wild? Thank you.

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That's a great question, so thanks for reaching out.

The most important consideration before approaching water purification is the contaminants you suspect are present in the raw water. If the water contains bacteria and protozoan cysts, as most lakes and streams do, then there lots of easy options to purify it. These include:

• Boiling
• Micro-filtering (e.g. passing it through a LifeStraw or Sawyer Mini filter)
• Chemical purification (e.g. iodine or chlorine tablets, or household bleach)
• Ultraviolet purification (e.g. using a SteriPen)
• Solar purification

The SODIS method can be used to kill bacteria present in water. See the linked article above for more info.

Some water sources, such as those in developing nations with limited plumbing or those which may have been contaminated by sewage runoff (or floodwater that contains sewage), may also contain viruses such as norovirus, rotavirus, or hepatitis. Viruses are smaller and more difficult to remove, so if you're buying an off-the-shelf purifier, look for one that is rated for virus removal. Brands such as Aquamira, Grayl, LifeSaver, and MSR offer purifiers in this category. For more info, see our H2O Hygiene water purifier buyer's guide.

However, the most challenging contaminants to remove are dissolved chemicals, since they are present on a molecular level. Micro-filters won't remove them, and boiling will only increase their concentration. Examples of water sources in this category would include seawater, urine, or agricultural runoff. This is where distillation is valuable — it physically separates the water from most chemical contaminants.

An example of a traditional copper still.

The classic distillation device is a still, much like what bootleggers used to make moonshine. These generally consist of a copper vessel over a fire, with a condenser coil that cools water vapor and deposits it into a clean container. As you'd expect, stills are usually heavy and not very portable.

If you need a portable way to distill water in the wild, you'll need a way to boil it, trap the vapor (steam), and cool it so it condenses back into liquid. It's possible to do this with two glass bottles, or with a pot, aluminum foil, and a glass jar. It's also possible to build a solar still, but that method will only generate a small amount of water each day.

Unless you're concerned that your water source may be contaminated with salt and/or harmful chemicals, we'd recommend using one of the simpler methods of purification we mentioned, since they will require much less equipment and time.

Hopefully this helps you as you begin learning more about prepping.

If you have a survival-related question of your own, you can email us at offgrid@recoilweb.com.

Written by Patrick McCarthy