FanVancouver · Local guide
Water in the BC Backcountry — Finding It, Treating It, Not Getting Sick
Choosing a water source in BC, filter pore sizes, boil times at altitude, chlorine dioxide wait times, glacial silt, melting snow and dehydration.
FanVancouver · Local guide
Choosing a water source in BC, filter pore sizes, boil times at altitude, chlorine dioxide wait times, glacial silt, melting snow and dehydration.
Home · BC Camping · Survival · Water
Skills · Filters · Boiling · Glacial silt
British Columbia has more clean-looking water than almost anywhere on earth, and clean-looking is not a treatment method. Giardia does not change the colour of a stream.
Ranked from best to worst, all other things equal:
Things that are not water sources: seawater (it costs you more fresh water to process than it returns), your own urine, and alcohol.
| Threat | Size | Beaten by |
|---|---|---|
| Protozoa — *Giardia*, *Cryptosporidium* | 1–15 µm | Filters, boiling, UV. *Crypto* resists chlorine and iodine; chlorine dioxide needs up to 4 hours |
| Bacteria — *E. coli*, *Campylobacter*, *Salmonella* | 0.2–5 µm | Filters, boiling, all chemicals, UV |
| Viruses — norovirus, hepatitis A | 0.02–0.4 µm | Boiling, chemicals, UV. Most backpacking filters do not remove viruses |
| Silt and organics | varies | Pre-filter, settling, activated carbon |
| Heavy metals, mine tailings | dissolved | Nothing you carry. Avoid the source |
In remote BC backcountry, protozoa and bacteria are the realistic risks and a good filter handles both. Viruses matter more where there is human traffic upstream — busy frontcountry lakes, popular canoe circuits, anywhere downstream of a settlement. If you are unsure, combine methods.
Health Canada and the CDC agree: bring water to a rolling boil for 1 minute, and for 3 minutes above 2,000 m. That is it. Longer boiling is fuel wasted, not safety gained. Boiling kills everything biological, works on cloudy water, and needs no maintenance — its only cost is fuel and time. Budget roughly 100 ml of white gas or 15 g of canister fuel per litre boiled.
Look at the rated pore size, not the marketing.
A UV pen treats a litre in about 90 seconds and leaves no taste, but it needs clear water (pre-filter silty sources), batteries that work in the cold, and an unbroken lamp. Excellent as a primary in clear alpine country, poor as a sole method on a long trip.
Do not eat snow. It costs roughly 80 calories of body heat per 100 g melted internally, and in cold conditions that heat is your life. Melt it.
Melting technique matters: start with a small amount of liquid water in the pot ("primer water") before adding snow, or you will scorch the pot and produce a burnt taste. Snow is around 10:1 by volume — a full pot of powder yields a disappointing centimetre of water. Budget fuel accordingly; winter trips typically use two to three times the fuel of summer ones.
Melted snow still needs treatment if it has been on the ground, and it is flat-tasting and mineral-free. A pinch of electrolyte fixes both the taste and the sodium loss.
Rain and dew are drinkable with basic treatment. A tarp funnelled into a pot collects surprising volume in a coastal storm; dew wiped from grass with a bandana at dawn and wrung into a bottle is a genuine emergency technique.
Baseline is roughly 2–3 litres a day at rest in moderate conditions. Hiking with a pack in summer heat pushes that to 4–6 litres, and more at altitude, where breathing dry air costs you water you never notice losing.
The early signs, in order: dark urine, thirst, headache, irritability, poor decisions. That last one is the dangerous one — dehydration degrades judgement before it degrades legs, and most bad backcountry decisions are made by someone who has not drunk since breakfast.
Not safely. Giardia is present in BC watersheds, including high alpine ones, and it does not affect how water looks or tastes. The risk on any single sip is low; over a week of drinking untreated water it is not. Treat everything.
One minute at a rolling boil, or three minutes above 2,000 m elevation. Boiling longer does not add safety, it only burns fuel.
Most do not. A typical 0.2 µm hollow-fibre filter removes protozoa and bacteria but passes viruses. That is acceptable in remote BC backcountry and less so downstream of settlements or busy campgrounds — combine with chlorine dioxide or boiling if you are concerned.
Let it settle for several hours or overnight and decant the clear water off the top, then filter or boil. Pushing rock flour straight through a hollow-fibre filter will clog it, sometimes permanently.
Yes. Melting snow inside your body costs a significant amount of core heat at exactly the time you cannot spare it, and it does not rehydrate you efficiently. Melt it in a pot, ideally starting with a little liquid water to prevent scorching.
Not legal or medical advice. Current regulations, park signage and professional training override this page. Emergency 911 · RAPP wildlife line 1-877-952-7277 · Report a wildfire 1-800-663-5555. Updated 2026-09-27.
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