Quick Answer
Sunlight can be used to execute a water purification method called solar disinfection, also known as SODIS. This method involves placing a clear plastic bottle in direct sunlight for a specified period to kill bacteria and other microorganisms in the water. The duration and effectiveness depend on several factors.
Understanding SODIS
Solar disinfection (SODIS) is a low-cost and simple method for purifying water using sunlight. It works by exploiting the UV rays present in sunlight, which are lethal to many bacteria, viruses, and other microorganisms. Clear plastic bottles are ideal containers for SODIS, as they allow UV rays to pass through while keeping the water from evaporating.
Preparing for SODIS
To use SODIS effectively, it’s essential to follow a few guidelines. First, fill a clear plastic bottle about 1/4 to 1/3 full with water. Next, place the bottle in direct sunlight, ideally on a surface that receives at least 6 hours of direct sunlight per day. It’s also crucial to note that SODIS is most effective at high altitudes and near the equator, where sunlight is stronger.
Implementing SODIS
Once the bottle is placed in direct sunlight, it’s essential to monitor its temperature. The ideal temperature for SODIS is between 40°C and 60°C (104°F to 140°F), which usually takes 6 hours. However, this duration may vary depending on the climate and the amount of water in the bottle. To ensure the water is safe to drink, check for any remaining bacteria or viruses by observing the water’s clarity and odor. If the water still appears cloudy or has a foul smell, it’s best to repeat the SODIS process.
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