PSR ExpertPrimitive Survival Rating

Safe Water

Boiling

The gold-standard field treatment for pathogens when you can bring water to a rolling boil—ancient practice wherever fire and a vessel exist.

1 min readMedium energyHigh reliability

At a glance

Energy investmentMedium energyFuel is the cost. In wet biomes, gathering dry fuel may exceed the boil itself.
ReliabilityHigh reliability
Time15–40 minutes including fire and cool-down

Materials

  • Fire and fuel
  • Heat-safe vessel (metal, ceramic, rock-boiling in a pit with hot stones)
  • Settled or pre-filtered water

Steps

  1. 1Pre-filter cloudy water through cloth.
  2. 2Bring to a rolling boil and hold it for one minute—three minutes above about 2,000 m (6,500 ft).
  3. 3Cool covered; store sealed.
A soot-blackened pot of water at a rolling boil on stones over a small wood fire, with a lid and a cooling container beside it
A rolling boil is the one field treatment that needs no judgement call about germs—though it does nothing for chemicals.

Common mistakes

  • Vessel cracks or spills—lose both water and fuel
  • Assuming boil removes chemical pollution
  • Recontaminating with dirty lids or hands
  • Heating wet or porous river rocks for rock-boiling—they can crack or explode

Region fit

Best in: Temperate forest, Tropical jungle, Mountains, Snow & ice, Coast & swamp · Poor in: Desert

  • Temperate forestGood fit
  • Tropical jungleGood fit
  • DesertPoor fit
  • MountainsGood fit
  • Snow & iceGood fit
  • Coast & swampGood fit

Fit keyGood fitPoor fitAvoid

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