The usual method of collecting a small amount water in the Australian outback where salty water is available but not
drinkable is to use the method as illustrated in fig one.
A hole is dug into the ground into which a small cup or collection container is provided.
The earth surrounding the hole is covered with water but not saturated .
A clear plastic sheet is then placed over the area surrounding the cup and the hole and held in placed with
soil or some other means.
A small rock or bearing is placed in the middle of the plastic sheeting so that when the sun evaporates water from
the soil it runs down the plastic incline and towards the cup where the water collects.
Where water is not readily available fresh plant material can be placed around the cup and the water will be drawn from
this material.
This my idea for a better version
Parts sizes are not critical and hopefully not cost you much as the idea is to use recycled materials and parts
which can be substituted for those below.
you will need.
One large tin can ex coffee can ideal holds about 2.5 kilos (must have good lid ).
A smaller tin can that can fit comfortably inside the larger one with approx 1 inch gap between the inner and outer can
and one or two inches lower than outer can.
A quantity of river sand .preferably soil with no clay content or other bead like material
One empty 1 litre plastic coke cool dink bottle.
One larger size coke bottle to hold your salt water supply. ( 2 or 3 Litre) with plastic top
Some rust proofing paint (black).
A small micro irrigation tee piece and some plastic tubing
a small micro irrigation hose joiner with screw thread both ends.
If you wish to stop your tin cans from rusting you will need to paint all tin surfaces with anti rust paint except
the top lid on the outside can.
When you have done this drill a hole in side in the larger can a bit below the level the second can will occupy
and fix into position the tee connection with end down. and one end out at right angle to the can.
This will be the position where you water supply will enter.
Now place river sand between the spaces below and along sides the two cans will sit , try have even spacing between the two cans.
Cut the upper part of the I litre coke bottle top off
With the upper tin can lid you will need to cut a circular hole that will allow the fitting the bottom part of the plastic coke bottle (Push the bottom of the bottle from the top side of lid downwards.
which will need to fit snugly (you can use sealer or glue or tape wrapped around the plastic bottle to hold it
from slipping past the desired level when you fill it with water.) make it airtight as possible with sealant ect.
one or two holes will need to placed in top of lid with reversed bicycle tyre tube valves to prevent over pressurisation of unit. threads screwed into holes from top of can lid
Inside of the smaller can you will need a plastic water collector cup than can be easily removed when filled with the pure water.
With the coke bottle cap insert the screw thread connector into the plastic cap top and make water tight.
Fill bottle with water and turn up side down and see that water comes only from inside the screw connector thread (this is your water supply bottle)
Next connect to the connector on the larger can with some micro irrigation hose and watch if the water level rises in the sand above and into the centre can if it does you will then need to lower connection insertion point
If you want it to be simplier just pour some water into the sand until filled level (you may need some sort of hose or of funnell to do this without getting water in the centre can though. If the above is okay place lid on unit and fill the cut plastic bottle with water and place in sun..
Don't use the first few water recoveries as it may contain impurities from the rust paint and glue you may
use in the construction of the devices
The black painted unit is placed in the Sun
Water flows from the water supply bottle and find it own level ( something like automatic pet water suppliers)
in the sand mixture between the two cans.
The Sun heats the outer tin and heats up the water in the sand causing evaporation.
Water vapour is then given off and moves towards the central water bottle where it condenses and drips down into the
water collection container below.
By removing the top lid this water can be taken and used.
The sand may also act as an insulator and keep the inner can cooler and help in water recovery.
I believe other heat sources could be used to cause evaporation as long as not too hot to melt plastic components
Remember to remove and use clean sand when it has been saturated with salt.
Let me know how your unit works
Geoff
