This Water Reservoir is Covered with 96 Million Shade Balls
The balls are there to stop the sun from triggering a chemical reaction that turns harmless bromide into carcinogenic bromate.
YouTuber Veritasium took a boat through the Los Angeles reservoir that it turns out is covered with 96 million black balls. Why? Well, he explains it in his video along with his video description.
"I took a boat through 96 million black plastic balls on the Los Angeles reservoir to find out why they're there. The first time I heard about shade balls the claim was they reduce evaporation. But it turns out this isn't the reason they were introduced," said Veritasium.
"The balls are made of high density polyethylene (HDPE) which is less dense than water so they float on the surface of the reservoir even if they break apart. They are 10cm (4 inches) in diameter and contain about 210ml of water. So the main reason they are on the reservoir is to block sunlight from entering the water and triggering a chemical reaction that turns harmless bromide into carcinogenic bromate. This effect occurs with prolonged exposure to bromate so regulators insist that levels be kept below 10 microgram per liter on average over a 12 month period."
The video gives an excellent description of how the balls work complete with illustrations but the best part by far is seeing all the balls in the reservoir. We won't tell you anymore. You have to watch it for yourself.