Pure water is essential. Any water found in the outdoors can be contaminated with any number of diseases. Water can play a major role in the transmission of infections. If you use water from a natural water source, it is advisable to purify it to kill any microorganisms which can cause diarrhea, cramps, dysentery, or other more serious health problems. There are numerous methods of water purification.
| Boiling | Gypsy Filter | Chemicals |
| Distillation | Reverse Osmosis | Solar Still |
| Charcoal Straw Filter | Sediment Hole | Bamboo Filter |
| Sterilization Tablets |