purify-water

name	purify-water
locale	caveman
source_locale	en
source_commit	82c77053
translator	Julius Brussee homage — caveman
translation_date	2026-04-26
description	Purify water from wild sources using boiling, filtration, and chemical methods. Covers source assessment and priority ranking, sediment pre-filtering, method selection (boiling, chemical, UV, filter), altitude-adjusted boiling procedure, chemical treatment dosages, and safe storage practices. Use when needing drinking water in a wilderness setting, when available water sources are of unknown quality, in an emergency survival situation where dehydration is a risk, or when making water safe for cooking or wound cleaning.
license	MIT
allowed-tools	Read
metadata	{"author":"Philipp Thoss","version":"1.0","domain":"bushcraft","complexity":"intermediate","language":"natural","tags":"bushcraft, water, purification, survival, wilderness, filtration"}

Purify Water

Purify water from wild sources to make safe for drinking. Use field-available methods.

When Use

• Need drinking water in wilderness setting without access to treated water
• Available water sources of unknown quality (streams, rivers, lakes, ponds)
• Emergency survival situation where dehydration is a risk
• Need make water safe for cooking or wound cleaning

Inputs

• Required: Water source (flowing or still)
• Required: Container (metal pot, bottle, improvised vessel)
• Optional: Purification supplies (chemical tablets, filter, UV pen)
• Optional: Fire-making capability for boiling (see make-fire)
• Optional: Cloth or natural filter materials for pre-filtering

Steps

Step 1: Assess and Pick Water Source

Not all water sources carry equal risk. Pick best available source.

Water Source Priority Ranking (best to worst):
┌──────┬─────────────────────────┬────────────────────────────────────┐
│ Rank │ Source                  │ Notes                              │
├──────┼─────────────────────────┼────────────────────────────────────┤
│ 1    │ Spring (at the source)  │ Lowest contamination; still treat  │
│ 2    │ Fast-flowing stream     │ Moving water has fewer pathogens   │
│      │ (above human activity)  │ than still water                   │
│ 3    │ Large river             │ Dilution helps but agriculture/    │
│      │                         │ industry upstream is a concern     │
│ 4    │ Large lake              │ Collect from open water, not shore │
│ 5    │ Small pond or puddle    │ High pathogen and parasite risk    │
│ 6    │ Stagnant pool           │ Last resort; heavy treatment needed│
└──────┴─────────────────────────┴────────────────────────────────────┘

Warning Signs (avoid if possible):
- Dead animals nearby
- Algae bloom (blue-green scum)
- Chemical odor or oily sheen
- Downstream of mining, agriculture, or settlements
- No surrounding vegetation (may indicate toxic soil)

Collect water from below surface (avoid surface film) and away from bank edge.

Got: Clear or slightly turbid water from best available source. Collected in clean container.

If fail: Only poor sources available (stagnant, turbid)? Proceed but plan for aggressive pre-filtering (Step 2). Use multiple purification methods (belt-and-suspenders approach). No water source found? Look for indicators: green vegetation in valleys, animal trails leading downhill, insect swarms at dawn/dusk. Listen for running water.

Step 2: Pre-Filter Sediment