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Primitive water distillation construction notes and lessons learned

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  • MikeL
    Four different basic ways of distilling water are tested and the lessons learned are discussed. Gradient steps in complexity of construction are shown. Any
    Message 1 of 1 , Jan 13, 2005
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      Four different basic ways of distilling water are tested and the lessons
      learned are discussed. Gradient steps in complexity of construction are
      shown. Any one trying to distill water will most likely be going though
      the same learning pains. Hopefully if you read and understand this you
      can stand on what I have learned and start at that point to design what
      you can build taking into consideration what you have available to use.

      1) Can sheet metal or large surfaces be used to distill water evaporated
      from an open pan etc? Answer: Technically Yes, but practically No. If
      one needs a practical way to produce drinking water before one dies of
      thirst this method becomes very problematic. This method will produce a
      small energy inefficient amount. I was able to get about one or two
      drops every 10 sec by using this method. see open aluminum duct

      It is easy to produce way too much steam and overwhelm the cooling area,
      which needs to be as large as possible. If one produces too much steam
      it keeps the condensation area hot all the time and thus no condensation
      takes place. One will not be able to regulate the source of heat in a
      primitive environment thus this method could be a problem.

      Another big disadvantage is if the relative humidity is too low (say
      below 40-50%) then condensation will evaporate before it runs off. This
      method then will not then work. The source of heat whether burring
      wood, gas, or electrical has a tendency to produce hot dry air above the
      fire that will rapidly evaporate the condensed steam. In other words
      one needs to transport the steam a bit away from directly above the fire
      area before trying to condense it.

      Sometimes it helps to slightly cap off the ends to reduce the flow. See
      http://home1.gte.net/mikelob/Tea_Pot_ends_closed.JPG . If there are
      contaminates in the surrounding air that are settling out (like volcanic
      ash) then this open process will allow the distilled water to become
      contaminated again.

      Bottom line: The open-air process is the problem in this method it
      introduces too many variables. After a PS in a primitive environment
      one needs a controllable process that can be repeated under widely
      varying weather conditions.

      2) What about using a nearly closed area for condensing steam? This
      works better than the above open sheet method but is still not that
      practical in a primitive environment due to the need to carefully
      control steam flow, and the size of the cooling area needs to be large.
      Again too much flow easily overwhelms the surface area and will
      produce no or a small amount of distilled water. The heat from the fire
      producing hot air needs to be directed away from the condensing area.
      For this method one can use 10 foot galvanized steel roof rain down
      tubes, air-conditioning duct piping without insulation, or sheet metal
      vent pipes. The tests http://home1.gte.net/mikelob/3inch-Ducting.JPG
      were done using only one section of aluminum 3” vent flexible pipe 7 ft
      long. The open upper end needs to be nearly closed off so that it
      limits the steam flow. When properly adjusted, I was able to get 1 cup
      of water every 1.5 hour using this 3” by 7-foot method. If one had
      enough of these pipes and a way of directing the steam flow into each
      then one could produce sufficient water for drinking. One advantage of
      is this method is it can be made to limit the contaminants in the air
      from entering into the distilled output.

      Speculating now, if one had the space to do it, probably outdoors; one
      could build a porcupine looking half circle made out of 5-10 rain down
      spouts. One would take a bunch of these 8-10 foot rectangular tubes
      made out of galvanized steel, and join the open end (down ward
      direction) in a hemisphere shape. The upper closed end would have a
      small hole that could be adjusted by partly closing it off to maximize
      water output. I am thinking the ones that are nearly vertical would
      work best with a small air escape hole, and the ones that are more
      diagonal would work best with a slightly bigger hole. The water would
      collect on the inside as the outside cools off. As the water runs down
      the pipe and gets close to the end there could be smaller catching
      tubing that could be positioned to allow the water to run off into a
      collection point. The fire would be built off to one side and the steam
      diverted by use of air ducting into this hemisphere. Heat from the fire
      would be directed away from entering the tubes.

      Another idea: I bet one could take 2 garbage cans or two 55 gallon tanks
      or any 2 large metal containers and make a water distillation unit.
      Visualize two garbage cans lying horizontally on something that blocks
      it about 4 or 5 ft off the ground. Set the bottoms facing each other and
      flush with each other. In the center off to one side (not under the
      cans) visualize a fire built with water in a pan above it. Run an air
      ducting vent pipe from over the boiling water to divert the steam into a
      cut hole in each can. This would be big enough to allow the steam to
      enter near the bottom of each can (right over the steam). The cans have
      their lids in place and taped shut. A small hole (let the air out) may
      be needed in the lid to tune it up to producing maximum distilled output
      water. Because of the tapered shape of a garbage can the water would
      run toward the lid of the can and out into a small catching container.

      All of the above methods use air to take away enough heat to allow the
      steam to condense as water this takes a lot of surface area if no
      movement of the air is present. It would be much more efficient to use a
      fan on the outside of the cooling surface. However, in a primitive
      environment this will not be likely due to then need for electrical
      power, thus I did not do any testing in this direction.

      If one had available a car radiator or car heater unit turned diagonal
      and allowed steam into the top in a slow controlled way so that no steam
      came out the bottom then one could collect the distilled water as it ran
      out the bottom. This would take some cleaning and purging of used
      radiators to get all the foreign chemicals out.

      3) What about using a bucket of cold water and coils of copper tubing to
      condense the steam? This approach is basically building a simplistic
      water-cooled heat exchanger. The input reservoir can be a commonly
      available pressure cooker of any size. Alternatively the input
      reservoir can be made from any able to be closed container. Not much
      pressure is involved so theoretically it could even be made from a paint
      can in a pinch. I used a 4.2-quart aluminum pressure cooker that took
      about 15 min to start producing output once it is turned on from a cold
      start. Using the attached test set up
      http://home1.gte.net/mikelob/Coil_Exchanger.JPG and
      http://home1.gte.net/mikelob/coil_exchanger-detail.JPG I was able to
      produce about 6.5 cups/hour of distilled water. The input source was an
      electric stove 240 volt x 7.3 amps = 1750 watts. Note that water is
      replenished from the upper reservoir at the same rate it is turned to
      steam by adjusting the needle valve on the supply bucket and keeping
      tack of the level by use of the site gauge (silicon rubber hose) on the
      side of the pressure cooker.

      I found the water in the heat exchanger bucket gets extremely hot (from
      top down) and needs completely changing approximately every 35 min.
      This is a messy process in that when the tank is drained the copper
      coils get extra hot and the output hose and rubber seals get very hot.
      For good tasting water it is not good do to this extra heat on vinyl or
      rubber parts and it also tends to introduce leaks in the bottom of the
      exchanger tank where the copper tubing makes its seal with the stainless
      steel bucket. After a couple of hours of running I didn’t consider this
      design to be good enough for day-to-day production unit worthy of a
      primitive environment. One could defiantly not walk away from it and
      leave it unattended. It would take constant maintenance and attention.

      Also the resulting water had a strong vinyl taste to it. As a result, I
      don’t recommend using vinyl on any output part of the distillation
      system. Along the same line, any hydrocarbons (oils) that are in the
      water before distillation will end up in the output having been
      evaporated and then condensed back into the output water. Thus taste
      will be a problem using this method because of the estimated large
      amount of hydrocarbons (oils) found in the after PS available water.

      Also the method of measuring the water level in the pressure cooker
      needed some redesigning. Silicon rubber fish tank air hose will soften
      and swell up and eventually split open or leak at the ends. I initially
      tried to use this for a water level indicator and rapidly found it was
      not practical. Vinyl is worse it will swell, turn white, stretch and
      becomes very soft so it is not very usable on the hot output side.
      Glass tubing would work but is not available or practical in a primitive

      4) What about using continuous but controlled flow of cold water in a
      closed heat exchanger to condense the steam? What about, in order to
      improve taste, evaporating the dissolved hydrocarbons before introducing
      the water into the boiler? This approach is basically building a
      water-cooled heat exchanger by using copper pipes and fittings. See the
      linked test set up http://home1.gte.net/mikelob/Exch-Full.JPG. This
      approach also has incorporated lessons learned about heating and
      evaporating the hydrocarbons in the incoming water to the boiler. Note
      by dripping hot waste heat exchanger water into a small copper cup, it
      looses it hydrocarbons into the air. An efficient heat exchanger can be
      made out of .5” and 1” copper pipe and T-fittings for the end see
      http://home1.gte.net/mikelob/Exch-Full-1.JPG. Using the same electric
      stove producing 1750 watts and no insulation on the hot spots, after one
      hour I measure 2.8 Gal of 140 deg F waist hot water and 6 cups of output
      distilled water at about 16 degrees above room temperature or 86 deg F
      in my case. This is about 1.5 quarts/hr or 9 Gallons/day. More heat
      or more insulation and it would produce more output water. More units
      or a bigger pressure cooker and several heat exchangers running off the
      same pot in parallel would also produce more output.

      General Construction and Adjustment notes:

      Be sure to remove the bur off the inside of the ¼” copper pipe that
      solders to the open-air-replenish-cup. With the small hole the inside
      bur leaves after pipe cutting it will sometimes cause the cup to
      overflow (depending on surface tension of the water at the time).

      The saddle clamp needle valve was about 2.6 turns open for operation.
      The water valve to the bottom of the heat exchanger was open about 1/8
      to ¼ turn. I used a typical stop valve that has a rubber washer in it.
      This changes dimensions while in operation depending on temperature. The
      result is a need to constantly adjust the flow rate. I would recommend
      using a ½”gate valve instead. This has no rubber parts and the flow
      once adjusted will not change with temperature. See

      Rubber hoses works much better than vinyl but one cannot see though it.
      5/8-inch car heater hose was used for sealing the ½ inch tubing
      (outside diameter) that was slipped into the ½ inch copper pipe (inside
      diameter) of the heat exchanger. This same hose was used for the output
      wastewater. I don’t recommend using hose on the output of the heat
      exchanger for the good distilled water. If one gets steam coming out
      (too little water flow in the exchanger) then the taste of the hose will
      get into the distilled output water.

      The flow of cooling water in the heat exchanger can be adjusted by
      measuring how hot outside 1 inch pipe gets along it’s length. If one is
      careful one can use ones hand. Start at the cold end and gently move
      along the pipe to the point of needing to take ones hand off the unit.
      One wants to adjust the water flow so that it never gets hot at the cold
      end and is hot to no less than the center of the length. This is all
      depending on how much water you want to heat to what temperature.
      Generally one can do 130 to 180 degrees F for wastewater out of the heat
      exchanger without insulation.

      Measuring about 140 degrees at the boiler replenish cup is about
      typical. See http://home1.gte.net/mikelob/Replenish_Cup.JPG. If one has
      a lot of taste (hydrocarbon) in the result then one wants to get the
      replenish cup up to as high a temperature as possible by slowing down
      the cooling water in the heat exchanger. This will cause the
      hydrocarbons to boil out of the water as it drips though the open air
      between the needle valve and the open copper replenish cup. The cup has
      a baffled barer in it that blocks the surface of the input from reaching
      the output side. This keeps the lighter hydrocarbons (oils) on the
      input side until they evaporate. The output .25” tubing is positioned a
      bit off the bottom of the cup.

      Insolate to keep the heat in the cup on down to about 1/3 of the heat
      exchanger and the full length of the exposed ¼ pipe that goes to the
      pressure cooker See http://home1.gte.net/mikelob/Replenish-cup-Inso.JPG
      and http://home1.gte.net/mikelob/Exch-full-Inso.JPG. Insolate to
      keep the heat in the top of the pressure cooker and the pipe leading to
      the exchanger. This will make the operation more efficient.

      One can always make some charcoal by heating wood in a closed chamber
      and burning the gasses that come off to help produce the heat necessary.
      The charcoal can then be used to take the hydrocarbons out of the
      distilled water by filtering it though a container full of crushed
      charcoal. Hopefully this will be un-necessary if one can pre-heat the
      water enough to drive off the bad tastes.

      Silicon rubber II sealer seems to hold up well in the steam environment
      and can be used to seal the pipe going through the top of the pressure
      cooker if a rubber grommet is not available. See
      http://home1.gte.net/mikelob/Exch-Lid.JPG. A rubber grommet from the
      firewall or from the PVC valve from a junk after PS car may be able to
      be used. The grommet used for the safety valve in the pressure cooker
      may be able to be used. By the way I found the new “step drill bits” to
      be quite usefully in drilling the hole in the lid of the pressure cooker
      and when needed in the side near the bottom for supply 5 gallon buckets.

      A float was used to measure water level inside the pressure cooker. See
      http://home1.gte.net/mikelob/Float-Indicator.JPG. It was made out of a
      large inline disposable gas filter with the ends cut off and soldered up
      to make it air tight. See http://home1.gte.net/mikelob/Float-Hing-1.JPG.
      3/32” Brass brazing rod was used for the float hinge mechanism. Any
      other type of wire would also have worked including coat hanger wire.
      Small copper pipe about 3/16 inch was used for the outer hinge and was
      epoxied to the aluminum pot by use of copper epoxy. The copper epoxy is
      designed to replace solder and is sold at home improvement stores like
      Home Depot.

      The ½ inch pipe that comes out of the top of the pressure cooker and the
      inside pipe of the heat exchanger needs to be just big enough in
      diameter so as to not build up a back pressure in the cooker. Bigger
      pots and hotter fires may need a bigger pipe or more than one heat
      exchanger may be needed..

      Occasionally the pressure cooker will need to be shutdown and the
      contents empted out to dispose of the salts that build up. The frequency
      will depend on the dissolved mineral content of the water.

      Water taste: Using the copper coil approach the output had a strong
      vinyl hose taste. Using the last approach with the heat exchanger and
      the hot water dropped through open air to remove hydrocarbons before
      entering the boiler chamber resulted in very little taste.

      A bucket feed through for water outlet can be made using a barbed hose
      fitting with pipe threads or a needle valve. See
      http://home1.gte.net/mikelob/Bucket-Feed.JPG or
      http://home1.gte.net/mikelob/Bucket-feed-1.JPG or
      http://home1.gte.net/mikelob/Bucket-feed-2.JPG. Metal washers are used
      on both sides of the bucket. A coupling or another pipe fitting is used
      on the other side to tighten the washers down on the bucket side wall.
      Silicon rubber type II is used to seal the connection. Amazingly enough
      standard washer sizes work fine. For example for .25” pipe thread one
      uses two .5” metal washers.

      Summary: Open air-cooled steam distillation introduces enough variables
      that practical day-to-day distillation is not likely. Heat exchangers
      that make hot water as a by-product look the most promising for
      primitive water distillation.

      All of the above methods assume some sort of heat source that can
      produce steam. This assumption could be a problem for many areas due to
      the near constant rain and lack of firewood, coal, tar or other burnable
      resource. Some areas will be able to use hot earths crust to great

      Warning: Hot Steam, hot water and hot metal will cause server burns as
      it transfers it heat to the skin of the body rapidly.

      The amount of heat given off when steam changes back to water is 540
      calorie/gram (called heat of vaporization). The amount of heat it takes
      to raise one gram of water one degree C is 1 calorie. Thus one can see
      a lot of heat is capable of being transferred to the skin for very
      little amount of steam.

      Using these numbers it is easy to show that one can expect to produce
      hot waist water of about 7 (above 190 degree F) to 14 (above 140 degree
      F) times more volume of output water than the input water that was
      converted to steam in the first place. This assumes a room temperature
      of about 70 degree F as the starting temperature for the water.

      List of parts for the last approach, number 4:

      The unit was built to be broken apart and shipped in a standard home
      Depot box no bigger then 18” by 18” by 25”. Recommend using only lead
      free solder. Your prices might a bit different I included my current cost.

      Quantity - Description:
      2 coat hangers (used to make the support for each end of the
      exchanger) see http://home1.gte.net/mikelob/Coat_Hangers.JPG
      1 29” by .5” copper pipe (about $1.10)
      1 23.5” by 1” copper pipe (about $3.00)
      2 1” by .5” by .5” copper Ts (about $4.50 each)*
      1 14.5” by .5” copper pipe (about $ .60)
      1 4” by .5” copper pipe (about $.20)
      1 2” by .5” copper pipe (about $.10)
      1 .5” copper T (about $2.00)
      1 .5” copper 90 degree elbow (about $1.98)
      1 10.5” of soft copper tubing .5” OD (about $.80)
      1 .5”solder by .75” garden hose water valve ($4.25)
      1 20” by .25” copper tubing ($.30/ft)
      1 .25” Self – Tapping Saddle Valve or Gate Valve if you can find it
      1 1.5” copper end cap ($2.00)
      1 6 ft washing machine input rubber hose (3/8” ID) one end cut off ($6.00)
      1 6 ft of 5/8” car heater hose ($4.79)
      5 hose clamps ($.69/each)
      1 Barb 3/8 by 1/4 pipe tread for bucket feed though to hose. ($1.29)
      2 ½” washers for bucket feed though (one inside, one outside, silicon
      rubber seal in-between) ($.13/each)
      1 1/4 inch pipe coupling for bucket feed through (for inside bucket)
      1 Purolator (F20030) fuel filter (pep boys) for float in pressure
      cooker ($3.99)
      1 4.2 Qt Aluminum pressure cooker (Mirro brand $17.57 from Wal-Mart)
      1 3/32 inch Bronze welding rod. ($.25)
      1 3/16 small length section of copper tubing was used for float hinge
      1 5 Gallon paint bucket for supply water ($3.00)
      1 9/16” id rubber grommet ($1.54/3)
      1 ¼” ID rubber grommet ($1.54/6)
      1 pipe insulation ($1.19)

      Total is about $74 for parts.

      * This was the hardest item to find. I needed to go to a pipe supply
      place. I in a pinch believe you can use .75” x .5” x .5” pipe and
      fittings from local home improvement stores if you can not find this 1”
      T. The 1” versions are better and worth looking for see

      Assembly instructions after shipping to your destination:

      1) With the pressure cooker lid in you lap slide in the output pipe down
      from the top.
      2) Put the insulation on the top of the lid sliding it around the pipe
      if you are using it.
      3) Insert the .25” pipe into the lid from top down.
      4) Put the lid on the pot.
      5) Install coat hanger support on faucet end of exchanger
      6) Marry up the exchanger with the .5” pipe on the pot.
      7) Tighten all hose clamps.
      8) Hook up hoses to the supply bucket.
      9) Put a container under the end of the exchanger to catch the distilled
      10) Put water in the pressure cooker.
      11) Fire up the heat.
      12) Adjust the flow of water through the heat exchanger once producing

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