How to Filter Dirty Water With No Chemicals

In an emergency or while traveling in undeveloped areas, you can refresh your drinking water supply by filtering dirty water from a stream, well or rainwater collection. Never drink unfiltered water: Parasites and bacteria cannot simply be strained out; they must be killed before consuming. If you don't have chlorine bleach or tablets available or don't want to use chemicals, filter your water using a few basic supplies. High-end ceramic filters will filter and disinfect water in one step but are expensive and may be unavailable. Solar disinfection and boiling are both safe alternative methods.

Things You'll Need

• 2 clean buckets or large vessels
• Clean plastic 2-liter bottle or milk jug
• Fine, clean sand
• Coarse, clean sand
• Small, clean pebbles
• Coffee filter or tightly woven cloth such as canvas
• Rubber band or thin cord
• Clean plastic water bottle or cooking pot

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Instructions

Filtration

• 1

  Aerate the dirty water by pouring it back and forth between two clean vessels about 10 or 15 times. The water is properly aerated once most of the gas is released—at this point, bubbles should no longer form rapidly when pouring from one container to the other.

• 2

  Allow the aerated water to sit for approximately 20 minutes in one of the containers to allow large sediment to settle.

• 3

  Fill a clean plastic 2-liter or 1-gallon milk jug with about 2 inches of clean, fine sand. Layer another 2 inches of clean, coarse sand on top of that, followed by about 4 inches of clean pebbles. Cover the mouth of the jug with a coffee filter or piece of tightly woven cloth and secure with a thick rubber band or tightly tied piece of string.

• 4

  Turn the jug upside down and cut off the wide bottom of the jug. This will allow you to pour directly over the layer of fine sand.

• 5

  Hold the jug over the clean water bottle or cooking pot and carefully pour the water that has been settling into the jug. Stop pouring when you reach the bottom of the bucket, which should contain more sediment. Discard this dirty water.

• 6

  Allow the water to slowly filter through the sand, pebbles and cloth into the container, stopping when the water level is about three-quarters from the top of the bottle or cooking pot.

Solar Disinfection

• 7

  Screw the water bottle cap on and shake the bottle vigorously about 20 times.

• 8

  Continue pouring water into the plastic water bottle until it is full, then replace the cap.

• 9

  Place the filled, sealed water bottle on a roof or other flat, open area. Allow the sun to heat the water for at least six hours (or two days if the sun is obscured by clouds). Consume directly from the bottle or from a clean drinking vessel.

Boiling

• 10

  Place the cooking pot on a heat source such as an electric or gas range or cooking fire.

• 11

  Let the water come to a rolling boil. This stage can be recognized by a rapidly moving water surface with large, boiling bubbles; it is differentiated from a simmer, in which the surface of the water is relatively still and only small bubbles appear around the edges of the cooking pot.

• 12

  Boil the water for at least a minute. Allow to cool before consuming directly from the cooking pot or from a clean drinking vessel.