Why Are 96,000,000 Black Balls on This Reservoir?

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  • Published on:  Friday, May 10, 2019
  • 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.

    Huge thanks to LADWP for arranging this special tour for me. Next time let's put the GoPro on the submersible!

    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.

    Special thanks to Patreon supporters:
    Donal Botkin, Michael Krugman, Ron Neal, Stan Presolski, Terrance Shepherd, Penward Rhyme and everyone who provided feedback on an early draft of this video.

    Thanks to:
    Las Virgenes Reservoir for footage of initial shade ball dump
    Euro-Matic for bird into jet-engine footage

    Researched and Produced by Casey Rentz

    Animations by Maria Raykova

    Music from http://epidemicsound.com "Colorful Animation 4" "Seaweed"

    And from Kevin MacLeod "Marty Gots a Plan"

    This is an educational video about the science of water quality.
  • Source: https://youtu.be/uxPdPpi5W4o


  • Titanic


     an hour ago

    So how well would the Titanic move through shade balls?

  • Princess Azarcon

    Princess Azarcon

     7 hours ago

    Youtube: ohhh great darling you're one of the 39M viewers of this video.

    me: dude did you see the bird? (._.")

  • Fais kareem

    Fais kareem

     13 hours ago


  • Luhong Zhang

    Luhong Zhang

     14 hours ago

    Hi Veritasium, thanks very much for providing excellent videos for us, I have subscribe your channel for years. I have learned a lot from watching your videos. Moreover I was inspired by this video at this time. Instead of reducing the evaporation of water or preventing the generation of bromate, I really intend to accelerate the evaperation of the water by improving the balls into solid ones with mesoporous characteristic. As you know, Australia is a country surrounded by sea, but you cannot image how could it be a droughty continent with surrounding water. Australia has a dry climate, and forest/bush fires are easily triggered, especially in winter. However, with the deterioration of the global environment, the fires are more frequent and out of control in AU right now. So may I have the official website for the producer of the shade ball? If feasible, I really want to discuss with them about some technical issues. And the purpose for the improved balls is supposed to be used into accellerating the evaporation of water and regulating the climate in Australia and finally reducing the bushfires.

  • Oh Ngonoo

    Oh Ngonoo

     15 hours ago

    What a genius Mr. Beast!

  • dustiest spade

    dustiest spade

     16 hours ago

    Bro I'm not like that bro.

  • jackie b

    jackie b

     16 hours ago

    WoW !!!!!!!!!!!!!

  • Jane Bravo

    Jane Bravo

     17 hours ago

    I don't know why, but this video make me nervous, I'm the only one?

  • 땡이



    그래서 저걸 왜 부은거죠..? 뭔가 의미있는 일인거 같은데 뭔소리를 하는지 모르겠네

  • Gina Editz

    Gina Editz

     yesterday +1

    5: 52 who sat the bird fly into the jet?

  • Emir Aydoğmuş

    Emir Aydoğmuş


    vay amk

  • jrml7



    Every penalty failed by Ramos is there

  • Alp Eren Gül

    Alp Eren Gül

     2 days ago +2

    No one cares about fishes?

  • Nick Scheidt

    Nick Scheidt

     2 days ago +1

    Jesus loves you

  • Mark Russell

    Mark Russell

     2 days ago

    How long do they last before you need to replace the balls?

  • c3t


     2 days ago

    if anyone was wondering they spent like 3.2 million dollars on all those balls

  • Ian Mar

    Ian Mar

     3 days ago

    Just passed by this 😂

  • Mi MIC Tv 76

    Mi MIC Tv 76

     3 days ago


  • Noel Schaban

    Noel Schaban

     3 days ago

    Also wenn die Dinger aus Kunststoff bestehen dann chiou

  • Creeper 900

    Creeper 900

     5 days ago

    Greta thumberg wants to kill you