Safe drinking water is not always top of mind when we are out for a day of fishing or hunting. It’s easy to carry enough water to keep you hydrated for such an outing.

Water, however, weighs one kilogram a litre, so carrying enough to support a multi-day wilderness trip is not always a practical option. Fortunately, Ontario’s wilderness offers no shortage of fresh water to access. But is it safe to drink?

The prudent answer is to always assume no. Even water with pristine appearance can harbour bacteria, viruses, or parasites that possess the ability to ruin an outing, and possibly have long-term and potentially catastrophic effects on your health.

All this to say, you can do without a lot of things on a wilderness trip, but a method of ensuring safe drinking, cooking, and teeth brushing water is not one of them. Fortunately, we have some options to ensure your drinking water is safe.


Boiling is the surest and perhaps oldest way to kill harmful water-borne bacteria, viruses, and parasites, according to the US Center for Disease Control. The CDC advises bringing water to a rolling boil and keeping it there for at least one minute (and three minutes at altitudes over one mile.)


  • No special equipment or chemicals are needed


  • Requires heavy use of stove fuel or requires taking the time to build a fire
  • Does not remove particulates
  • Boiling is not a viable option if fires are prohibited

Gravity filters

These ceramic filter units, have screw-on water bladders attached. You fill the bladder with untreated water, then attach it to the filter. The unit is then hung with the bag above the filter so gravity feeds the water through the filter.


  • Easy to use
  • Some attach to other containers or bottles
  • Fairly easy to flush out
  • Convenient to use in camp
  • Lightweight and packable
  • No physical effort required


  • Canʼt let bladder freeze in winter
  • Generally processes small amounts

Straw filters

These units are very popular. They are essentially oversized straws with filters.


  • Inexpensive
  • Lightweight, compact and easy to pack
  • A good choice for an emergency kit or hunting backpack


  • Shorter filter lifespan than other styles
  • For individual use
  • Suction required to draw water through filter can be hard on the jaw after a while
  • Must be kept from freezing in winter after use

Pump filters

These units have hoses that are placed into the water source, a hand or electric pump that draws the water through a ceramic or pleated filter and an outlet hose so that water can be directed to the container which will receive the clear water.


  • Will attach to other containers such as Nalgene bottles
  • Filters lots of water quickly


  • Expensive
  • Less compact. Heavier
  • Requires regular post-trip maintenance
  • More labour intensive
  • Moving parts


Water purification tablets generally utilize chlorine and iodine as their active ingredients and, while all make water safer, brands vary in effectiveness.


  • Inexpensive
  • Easy to use
  • No heating or physical effort required
  • Lightweight, and very compact


  • Long mix and wait times. Some take almost an hour
  • Does not remove particulates
  • The taste can be an issue for some
  • Can be confused with medication

UV lights

This is a relatively new technology for outdoors use that utilizes shortwave ultraviolet light to disinfect your water. Immerse the lamp in the untreated water and it disrupts the DNA of bacteria, viruses and protozoa, rendering them harmless.


  • Quick to use
  • Compact


  • Expensive
  • Does not remove particulates
  • Requires a charge/batteries

The source

It is important to have a sense of the water source’s quality. For instance, if you are dealing with a water source where chemical or sewage run off takes place, find another source. Avoid stagnant water. When drawing from flowing water, have a quick look at what’s upstream. I once saw a moose carcass floating in a river that was thankfully downstream. Lastly, when purchasing any water filtration system, do you research. There are many options and quality will vary.

Originally published in the August 2022 issue of Ontario OUT of DOORS

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