SolarWater – separates fresh water from sea or dirty water, using the power of the sun

Above is the trial unit.

SolarWater is a low temperature thermal still. It

takes in cold brine or dirty water & with sunshine makes cold fresh drinking water & cold saltier or dirtier water.

1. SolarWater units use the sun to separate fresh water from brine or polluted water leaving a stream of saltier or more polluted water.

2. A solar powered pump pumps the brine/polluted water from the sump slowly round coils of clear plastic tube in the heater/ sterilisers. The sun’s UV kills the bacteria in the water and raises its temperature to the 40C needed by the still.

3. The still is completely made of blocks of expanded polystyrene 300mm thick bonded together – so any heat put in cannot get out.

4 The sump fills the still chamber with water vapour.

5 Above the sump is a condenser of a coil of PVC pipe through which cold brine/polluted water flows. This condenses the vapour which drips off to a drip tray is collected and runs out as warm fresh water.

6. This flows through a PVC tubel – up which runs a smaller pvc tube the bringing cold brine/polluted water in the other way. The cold brine/polluted water cools the fresh water which leaves cold. The cold brine/polluted water is warmed and flows into the sump.

7. More water flows into the unit all the time than flows out as fresh water. So the excess extra salty or polluted water flows out. This is hot and flows out again through a tube of PVC tube up which runs a smaller pvc tube bringing cold brine/polluted water in tube the other way. The cold brine/polluted water cools the excess extra salty or polluted water which leaves cold. The cold brine/polluted water is warmed and flows into the sump.

8. The solar heater/sterilising units are self tracking and kept pointing at the sun by drums half filled with water. They are shaded from the sun so that at dawn, they are completely shaded – at dusk completely exposed to the sunlight. The top half of the drums are filled with air. The water in the lower half also fills a ram to which it is connected. As the unit changes angle it picks up weights adjusted to keep the unit pointing directly at the sun throughout the day.

At sunset the drums cool & the weights return the unit to the starting position to await the dawn. Plus the solar powered pump stops pumping preventing the dumping of the internal heat into the cold night.

9. The angle of the axis of the units is adjusted manually each month.

10. Everything is made of PVC & styrene – impervious to warm brine, with a life of 20 years with occasional cleaning.