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In the Backcountry with Bri: make your own water filter

This Saturday, October 10, 2020, we are happy to be a part of AK State Park’s Families to Parks (virtual) Day, and we are looking forward to when we can get back to doing it in-person to see all our AK families out connecting to our amazing wild spaces. For this Families to Parks day, Bri is demonstrating the various water filtration and treatment systems. Water filtering is an essential part of being a successful outdoors explorer and therefore an important part of our program.

Without further ado, the following is Bri’s blog and video demonstration. Bri teaches our camp kids much of what she discusses in the video and we are happy to share this with you!

water filtration and purification – the basics

Want to hear a joke about dehydration?  Well…there isn’t one. You should always have plenty of water with you no matter what you are doing.  But don’t worry, you don’t have to strap gallon jugs to your pack or bike every time you go out and explore The Last Frontier. 

Sometimes the hardest question I ask myself is how much water I should expect to carry for any type of trip.  Sometimes it may boil down to how much water is available on the trail itself.  Will we pass any lakes? Will we be crossing any rivers?  Thankfully there are a plethora of systems that you can carry along that would best suit your needs.  Some that can filter mass amounts of water with ease, some that are very lightweight and some you carry with hopes you never have to use. 

Bri’s guide to water filtration and purification systems
Bri’s water filtration and purification tutorial – zoom to 5:00 for steri pen and 12:30 for Bri’s DYI backcountry water filter.

With any system you choose there are two basic principles that you are trying to achieve: filtering and purifying. 

  1. Filtration is generally the first step to remove any floating bits, like leaf litter, bugs, sand, etc.  Commonly this is done with a ceramic cup where the water molecules can penetrate but debris is too large.  Out on the trail or backcountry this can be done with a coffee filter or as simple as a bandana.  (see our DIY water filter kit below!)

Remember, this is only the first part of acquiring viable drinking water. 

2. The second step is purification, where you remove or kill any microscopic bacteria or germs that can cause you to get sick.  Most commonly in any system this will be done with activated charcoal, like the MSR TrailShot or MiniWorks filter.  In the case of emergency many people will use iodine drops or chlorine dioxide tablets, but this unfortunately gives the water an odd taste and you must wait a time to let the chemicals do their thing. 

After filtering, always purify and/or treat your water – clear water is not clean water!
Clear water is not clean water – always purify and treat you water before consumption! Also, we love SCIENCE!

Commonly, people will simply boil their water to kill anything that may be lurking in the clear water (as seen in the video above), but you also must keep in mind fuel availability if you are on limited fuel for a long trip – alternatively, budget extra fuel for water boiling every day.  Another option is using ultraviolet rays to kill off any germs, like in a Steri-Pen. 

Everyone has their preferences for their filters and my personal go-to for summer conditions is the Sawyer Squeeze which is light and easy to use and a perfect fit for both thru hikes as well as throwing in my pack for a simple day hike. The Sawyer Squeeze, however, cannot stand to be frozen.  In the winter I generally use boiling snow as my main source of water.  I hope you all find your ideal system and have a blast getting out and putting it to use! 


Our campers demonstrating their super DIY water filter.

If you ever get into a jam and need a quick way to get safe drinking water, here is our trick! The kids at camp have a ton of fun with this – Kids get a closer look at what is lurking in their water and are empowered at learning a way to help themselves. If you don’t have the exact materials at hand, that’s okay! Get creative, there is probably another way to accomplish the same goal. (We often don’t carry plastic bottles in the backcountry with us – alternatively, use a sock and layer it the same way as described below).

What you’ll need:

  • coal (burned wood from a fire pit)
  • dedicated bottle for clean water
  • dedicated vessel for collecting “grey” water (unfiltered, unpurified water)
  • bandana, sock/coffee filter/piece of scrap fabric.
  • hair tie or rubber band
  • sand
  • rocks
  • plastic 1 L or similar style drinking bottle, or a dedicated sock

STEP ONE: Create your filter

Carefully cut your plastic bottle in half. Take the piece of fabric or coffee filter and place it around the outside of the top half of the bottle, with the drinking part tucked into the center of the fabric of filter. With the rubber band or hair tie, secure the filter or fabric around the nozzle. Now, invert this part with the nozzle pointing down and crumble up your coal, placing it into the bottom. Most bacteria passing through will be captured and bound to the coal. On top of the coal, place a layer of sand, and on top of the sand, a layer of small pebbles or gravel.

Place your filter, point down, into your dedicated CLEAN water receptacle. Get your sibling (as demonstrated below!) to help you out.

Make your filter – make sure to NEVER mix the CLEAN and GREY water receptacles!

STEP two: filter your water

With your dedicated GREY water receptacle, collect water from your chosen source. Try to collect water from a fast moving stream or river vs. a stagnant pond or sluggish creek, to avoid as much as possible collecting debris and bacteria. In Alaska, try not to collect water from silty streams or water sources, as the silt will quickly clog your filter…but for this DIY filter, it won’t make a difference as it is passing through sand and coal anyway.

Pour your GREY water into your super awesome filter. The water will trickle through all those layers as debris gets blocked by the gravel and sand and most bacteria will become bound to the charcoal – science rocks!

STEP three: purify and/or treat your water

In spite of your super awesome filter, you will still need to treat and/or purify your water before consumption. There are a few different ways you can do this: iodine tablets, a steri pen, or boiling. Remember, clear water is not clean water! If you are truly in an emergent situation, the last thing you want is to have life-threatening diarrhea when you’re already dehydrated.

That being said, if you think you stand a good chance of self-rescue or assisted rescue within 24-72 hours, it is probably okay to drink water taken from a fast-moving source and filtered to the best of your abilities. Use your best judgement with the tools you have at hand.

after filtering water, you still need to treat, or purify it by killing bacteria that may be present. Remember – clear water is NOT clean water!

Iodine tablets or water purification tablets work well, but you must wait several hours up to a day until they work properly. Also, some people with shellfish allergies will not want to use this method, so this is best left as a last resort or patience-is-a-virtue usage.

The steri-pens are great for international travel and backcountry trips. (pictured above: a cool camper cleaning his filtered water with our steri-pen) They use UV light to kill bacteria, but take time – you need to follow instructions and wave your UV wand in the water until the process is complete.

Boiling your water is a safe standby. You must consider packing extra fuel just for this purpose if that is your dedicated way of purifying water. Boil for at least one minute to make sure all bacteria are killed.

Stay tuned for follow up blog posts about what might be lurking in that wild water as well as best practices… And always remember – clear water is not always clean water!