Drinking clean in the winter backpacking season

While backpacking on the Appalachian Trail or any trail for that matter, water can be an issue all year round. It does not have to be during the dry heat of summer that water comes in sparing supply. However, winter adds its own problem.

Josh getting water on the Appalachian Trail in Georgia.
Josh getting water on the Appalachian Trail in Georgia. Yes, shorts in late November. Winter doesn’t always equal snow.

When the temperature drops below freezing, it should be obvious that water freezes. However, some will see running streams and ground temperatures above freezing but forget that the water in your filter, bottles, and hydration bladders can still freeze. For example, take the MSR SweetWater Microfilter. It is a great water filter that withstands cold temperatures, but if you forget to take it apart and drain the water in below-freezing weather, you are in trouble. From experience, you cannot just let the excess water drain from the tubes. Take it apart and shake out the water. Expanding water equals a broken pump. There is very little you can do with a filter and no pump, which of course is why you should always have backup water purifying tablets (liquid drops can freeze as well).

While there is always the option for boiling water, it is not exactly the easiest method and requires packing extra fuel. There is also UV water purification such as with the SteriPen Adventurer Opti UV Water Purifier, but it is battery-operated and also prone to issues. It should not be used alone. Always bring water-purifying tablets. Cold weather is a battery killer. One option is to wear the SteriPen around your neck so that it stays warm against the body.

Some basic cold weather tips

  • Carry more than one water source. Do not carry a bladder alone. Carry a BPA-free bottle or two.
  • Before your morning or late-night hike starts, put warm water in your bladder and bottle. Be sure it is insulated with clothes inside the main compartment.
  • If you are drinking from a bladder, be sure to blow the water back down into the bladder after every drink but sip often to keep it flowing. Cover the tube as much as possible.
  • Avoid storing batteries, drops, water, UV purifiers, and other filtration systems on the outside of your bag or in the side compartments. Keep them inside the main compartment close to your back insulated with clothes.
  • When you bed down, never leave purification systems or water outside of the tent.
  • Put your bottles of water and purification systems inside your sleeping bag for the night.
  • If you have two to three people in your party, consider sleeping in the same tent. A friend and I slept in sub-arctic temperatures with my dog and the tent shielded the best we could from the wind. During the night, the temperature in the tent was [thankfully] only 22°F. Water will obviously still freeze inside the tent at that temp, but when it is not zero or below, the tent will be much warmer.

Life happens. Sometimes things will occur beyond your control, and you have to make do with what you have.

What if everything fails?

There may be a time that you find yourself in trouble and have no way to filter water. For instance, you learn like another friend and myself that if you do not drain the MSR filter correctly and take it apart, it will freeze and break the housing. We did not have the extra fuel or tablets to purify our water. Sure, there are all sorts of scary microscopic critters that can be found in different water supplies. However, you will die without water.

  • Know about your surroundings before you go. The water is safe to drink in many rivers and streams, but not always.
  • Don’t drink from standing water.
  • Try to find water coming out of mountains away from roads.
  • Don’t drink from areas with lots of animal or human traffic. Go upstream if possible.
  • You can use clothing to strain most larger sediments.


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