Schaub Purifier

For too many people in this world the only water available is unsafe to drink. We can empower the poor to independently make unsafe water into clean, safe water.

The guiding principle is the universal one for distilling. Evaporate the desired liquid (in this case water) and then re-condense and collect it. Boiling water is too energy intensive. So, just warm it a bit and let it evaporate at its own pace. The system is completely scaleable so producing more clean water simply means building another unit and another unit, etc.

How much will a one square meter device produce? Very conservatively, about 14 liters of clean water per day. At 42 degrees N latitude in midwinter, one square meter gets approximately 750 mJ from sunlight in 12 hours. ASSUMING that after inefficiencies, we can utilize 5% of that daily energy, then we can expect some 35 mJ per day available to evaporate water. This is 35,000 kJ/day. Thus, using the 2454 kJ/liter enthalpy of water (at 20oC), one square meter can evaporate about 14 liters of water per day using 5% of midwinter sunlight. Summer sun and lower latitudes, of course, will produce more.

What about at night?

In addition to using sunlight, we can also run a chimney through the unsafe water holding tank to warm the unsafe water. This chimney does NOT have to be from a dedicated fire. This chimney can capture some of the waste heat coming off a cooking fire, fire place, flame used as a lamp, etc. For example, some people will take the partially burned wood of a cooking fire and leave it to burn out feeding heat to the Schaub Purifier. The fire will go from flames to dying embers and we want to capture as much wasted heat as we can.


Simple to understand, build, and manually operate.

Runs on solar power and wasted heat.

Distills clean water from pretty much any water, no matter how filthy.

Can be built from scraps by any one good with tools, anywhere in the world.

No moving parts.


Frequent cleaning needed because of mold, etc. and because of residue from the evaporated unsafe water.

Distilled water does not taste good. We humans will want flavorings.


  1. 1) Wicks hang down from the Cloth and into the tank of unsafe water.
  2. 2) Water climbs up the Wicks and into the Box by capillary action.
    1. The Cloth will always be wet, but not over loaded with water.
  3. 3) Window lets sunshine through.
  4. 4) The Cloth gets heated by sunshine.
  5. 5) As air and unsafe water get heated by the Cloth the air collects evaporated water.
  6. 6) Warmed, moistened air rises past the waxed Top with minimal condensation.
  7. 7) When warmed, moistened air hits Window, water condenses onto Window.
  8. 8) Clean water drips down Window and into Gutter
  9. 9) Gutter directs clean water to a container.
  10. 10) Cooled, dried air falls to the Cloth to begin the cycle again.


    1. Evaporation will leave solid contaminants, germs, etc behind.
    2. Dissolved liquids with lower enthalpies than water can come through into the clean water; alcohol and gasoline for example.
    3. All joints should be sealed watertight. The holes for the Wicks will automatically balance air pressure inside with ambient air pressure.
    4. While professionally manufactured systems would be best, serviceable DIY versions can be built using scraps salvaged from junk yards. For example, pipes can be assembled by cutting and gluing aluminum cans and/or plastic bottles.
    5. The exact sizes and shapes of components are NOT important.
    6. There are no supporting structures discussed because they do not matter to the functioning of the device.
    7. A Schaub Purifier can be mounted on a moving vehicle/boat.
    8. This design example assumes the water tanks are filled and emptied manually.
  2. BOX
    1. The Box can be any water proof, rigid material, or a water proof soft material backed by a rigid material. Joints need to be sealed water tight.
    2. Shown at 45 degrees off horizontal. Optimal angle will vary by location and time of year
  3. TOP – Wax the inside of the top. This will minimize condensation as the hot moisturized air travels from the Cloth to the Window.
    1. Window has to be clear to let maximum sunlight through to the Cloth. Glass, acrylic sheets, plastic sheets, even plastic film can all be used
    2. Set the Window to just past vertical leaning slightly away from the Cloth. This will help keep descending drops of water on the Window even when the Window vibrates.
  5. GUTTER – Gutter collects and guides the distilled water to container(s).
  6. CLOTH
    1. Should be black to maximize sunlight absorption.
    2. Choose a cloth that facilitates capillary action.
  7. WICKS
    1. Select cloth or string that facilitate capillary action strong enough to bring water up from the Unsafe Water Tank and let it spread into the Cloth.
    2. Space these so that all of the Cloth is always damp.
    3. The lowest Wick defines the max fill line for the Unsafe Water Tank so that water does not flow into the Box through the hole for the Wick.
  8. CHIMNEY – Level to allow for widely varied levels of left over heat.

This paper gives you my version based on my best beliefs and understanding. However, you do not need me. Make your own version based on your understanding and independently produce your own safe water!

May God bless you, Phil

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