Adventure Plans

1. Why water is your highest priority on trail

You can go days without food but hours without water before it starts to affect your performance and safety. Dehydration decreases endurance, impairs decision-making, and causes headaches — things you really don't want when you're navigating remote terrain with a heavy pack.

Planning your water carefully before each day's walk is one of the most important habits to build.

2. How much to carry

As a guideline, most hikers need 0.5L per hour of active hiking in moderate temperatures, and more in heat or at altitude. You rarely need to carry the entire day's water at once, but you do need to know where the next reliable water source is and always have enough to reach it with some margin.

In practice, carrying 1.5–2L is usually sufficient between sources that are spaced 3–4 hours apart. In drier environments or on exposed ridgelines where sources are scarce, plan to carry more.

3. Finding water sources

Before heading out, identify water sources on your route using:

• Topographic maps — rivers, streams, and tarns are marked. Blue lines and symbols indicate water.
• Komoot and Gaia GPS — often have water sources flagged by the community.
• Trail notes and route guides — well-documented trails frequently note reliable vs seasonal sources.

Bear in mind that water sources marked on maps can dry up in summer or in drought years. Always have a backup plan for the next source along the route.

Good sources: Fast-flowing streams and rivers with visible catchment above the snowline are usually clean. Mountain tarns (still lakes at altitude) are generally reliable but treatable.

Sources to be careful with: Water downstream of farmland, bogs, or heavily used campsites. Still water in lowland areas. Water near mine workings — some treated waterways carry minerals that filtration won't remove.

4. Treating your water

Unless you are very confident a source is uncontaminated, treat your water before drinking. The risks include Giardia, Cryptosporidium, bacteria, and viruses — all of which can cause significant illness with a delay of several days, meaning you might feel fine on trail and very unwell when you get home.

Your main options are:

Hollow fibre filter (e.g. Sawyer Squeeze, BeFree) — filters out bacteria and protozoa (including Giardia and Cryptosporidium). Fast, reusable, no chemicals, and no waiting. The Sawyer Squeeze is arguably the most popular lightweight water filter on the market. Not effective against viruses, which are rarely a concern in the backcountry of developed countries but worth knowing about.

Chemical tablets (e.g. Aquatabs, Iodine) — lightweight and cheap backup option. Effective against bacteria and viruses, less so against Cryptosporidium. Require 30–60 minutes of contact time. Fine for use in genuine emergencies or as backup.

UV pen (e.g. SteriPen) — kills bacteria, viruses, and protozoa quickly. Requires clear water (sediment blocks UV) and battery power. Works well but adds cost and a battery dependency.

For most UK and European hiking, a hollow fibre filter alone is sufficient and is our go-to recommendation. If your route includes areas with higher contamination risk, combining a filter with chemical treatment covers all bases.

5. Carrying water

Soft flasks — lightweight collapsible bottles (like those from Hydrapak or Platypus) work well with hollow fibre filters and pack flat when empty.

Hard bottles — Nalgene and similar brands are durable, easy to clean, and can handle boiling water. Heavier but very reliable.

Hydration bladders — convenient for drinking on the move without stopping, but harder to refill quickly and trickier to see how much you have left.

We use a combination: a 1L filter-compatible soft flask for treating and drinking, and a 1L hard bottle as backup and for camp cooking.

6. Drinking enough

Thirst is a lagging indicator — by the time you feel thirsty, you're already mildly dehydrated. Get into the habit of drinking at every rest stop, not just when you feel like it. Your urine should be pale yellow; dark yellow or amber means drink more immediately.

In cold weather you'll still need plenty of water even if you don't feel thirsty — the cold suppresses the sensation.