Why Are 96,000,000 Black Balls on This Reservoir | Veritasium
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updated 01 Aug 2023
The video explains the use of shade balls, black plastic balls, in a Los Angeles water reservoir to block sunlight and prevent the formation of carcinogenic bromate from bromide reacting with chlorine. The shade balls also reduce algae growth and water evaporation, making them cost-effective for water quality maintenance.
The video discusses the use of shade balls, which are black plastic balls, in a water reservoir in Los Angeles.
The main purpose of the shade balls is to block sunlight and prevent the formation of bromate, a carcinogenic substance, when bromide in the water reacts with chlorine in bright sunlight.
The shade balls are made of high-density polyethylene with carbon black, making them safe for contact with drinking water and stable in the sun for up to 10 years.
The shade balls also have additional benefits, such as reducing algae growth and evaporation by 80 to 90% in the reservoir.
They were initially used to deter birds from landing on the water's surface but were later found to be effective in preventing bromate formation.
The shade balls are cost-effective due to the savings in chlorination and reduced water evaporation.
There were attempts to use other shapes like hexagonal balls, but the round shape of the shade balls was found to be more effective in covering the water surface as it fluctuates.