Outdoor Leadership Curriculum Project

Water Purification in the Backcountry (New)

There are several different methods of water filtration. While there is not always a right water filter to use, some are less ideal than others. A couple of things to keep in mind when collecting water to filter.

1. Look for running water. This is generally cooler, less turbulent, and will have less likelihood of having algae, bacteria, and viruses in it
2. Try to find clear water. The more turbid (muddy) water is, the harder the water will be to filter, and the shorter the filter will last.
3. Try to avoid getting “chunks” in your water you plan to filter. These chunks, whether organic material or sand can clog a filter. These chunks also will slow any chemical filtration.

Chemical

Chemical water treatment uses different chemicals like iodine, bleach, or chlorine to kill off bacteria and viruses and filter the water. Chemical filtration does not filter out dissolved solids or any solids for that matter. Oftentimes chemical filtration will have a bit of a chemically aftertaste to the water. Chemical filtration is lightweight and is great for cold weather where other filters will freeze up. Most chemical treatments take 30 minutes to purify the water. Different brand names of this type of water filtration are:

• Aquamira is a two part solution that mixes to purify water. Rather than a chemically taste it tastes of lemons!
• Aquatabs is an iodine based water treatment in the form of little tablets.
• Bleach. You should use 2 drops per liter of water. If water is cloudy add an extra two drops
• Iodine. You should use 5 drops per liter of water. This gives the water an essence of band aids. If any participants are allergic to shellfish they should not use this as the compounds in shellfish are so similar to iodine that they could cause an allergic reaction.

Mechanical

Mechanical filters are the most commonly used filter in the outdoors. They are reliable, fast, and safe to use. The only major cons of mechanical filters is that they do need to be back flushed every now and then, they are often bulky, and they can not freeze. If a mechanical filter freezes it compromises the integrity of the filter or the filtration material and will lead to unfiltered water.

• Pump Style Filters. Pump style filters are great for a group, place the dirty water hose of the filter in the nearby water source and pump away! These are the bulkiest option but are fast and easy to use.

• Straw Style Filters. Straw style filters are a last resort solution. They are uncomfortable to use, are slow, and have to put a mouth on the filter.

• Gravity Filters. Gravity filters while being slow and large are a great set and forget filter. These are a great option for large groups when you want to set up a filter at camp for multiple people.
• Bag and Nozzle Filters. These filters, like the Sawyer squeeze are easy to use and are very pack able. These are great for smaller groups.

Boiling

Boiling is a great water purification method. Especially when snow is present in the winter and running water is hard to find.

• When boiling water be mindful of the risks of open flames/hot pots
• Water should reach a rolling boil for at least two minutes before the water is considered purified
• If you plan to pour the water into a water bottle make sure the water bottle is placed on the ground to prevent the spilling of hot water and potentially burning someone

Ultraviolet Light

Ultraviolet filters are relatively new and rely on batteries to function. These filters are fast, compact, but can struggle in colder weather

• UV filters don’t work great for large groups as you can only filter about a liter at a time
• They can also be unreliable. Bring an extra filter type as a back up.

Bringing a lot of Water

On some trips (where there is a basecamp that is vehicle accessible) a viable option is bringing lots of water in a large container. Always bring more than you might think you need.