Quick Answer
A solar still pit should be 6-8 inches deep to allow for efficient evaporation and condensation of water, while minimizing the risk of flooding. This depth also facilitates easy access and maintenance. A slightly sloping bottom aids in drainage.
Designing the Solar Still Pit
When building a solar still, the pit’s depth is crucial for effective water collection. A depth of 6-8 inches (15-20 cm) is ideal, as it balances the need for sufficient water evaporation with the risk of flooding. This depth also makes it easier to access and maintain the still. A slightly sloping bottom, around 1:10, aids in drainage and prevents water from accumulating at the bottom.
Calculating the Pit’s Dimensions
To determine the pit’s dimensions, consider the following factors: the size of the collection tray, the number of people relying on the still, and the local climate. A general rule of thumb is to use a pit with a diameter of 3-4 times the diameter of the collection tray. For example, a 12-inch (30 cm) collection tray would require a pit with a diameter of 36-48 inches (90-120 cm).
Building and Testing the Solar Still
Once the pit is dug, line it with a waterproof material, such as plastic sheeting or a tarp. Place the collection tray on top of the pit and weigh it down with rocks or sand. As the sun heats the water, it will evaporate and condense on the underside of the tray, dripping into a clean container. Test the still by adding a small amount of contaminated water and measuring the output to ensure it is safe for drinking.
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