Solar Stills

In desert areas or where there's a scarcity of water, some people make use of solar water stills. This technique is also used by the military when they have to be in such areas and cannot find other natural sources of water.

So, how do you make a solar still? It's very simple and cheap. Get a transparent sheet of plastic, about 4 x 6 feet. Now, dig up a hole / pit in the ground, about 3 x 5 feet and about 1 foot deep. Place a cup, mug or any vessel at the center of this hole. Cover the hole with the clear plastic sheet and place some weight on all sides of the sheet to make it air tight. You could place mud that you dug up from the ground, stones or anything similar that is available for the purpose.

Water Turbidity

Here in Mumbai, especially during rainfalls, the municipal water coming out of the taps becomes quite turbid or muddy. For making it clear, most people make use of alum. They put the water first into a container, move a piece of alum along the water surface in circles, a few times and then let the water remain standing in the container for a few hours to make the bad stuff settle at the bottom. Then the clean water can be poured into another container.

Due to the high turbidity of water, at times while using alum, I had to use alum for a longer time to make the bad stuff settle down. The water became crystal clear in a few hours, but it was difficult to drink - It had a sour taste. So, I searched for other methods for treating turbid water. There were a list of substitutes to alum for treatment of turbid water, on wikipedia but none easily available.