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

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.

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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

And from Kevin MacLeod "Marty Gots a Plan"

This is an educational video about the science of water quality.

[matthewjones]

It takes a lot of balls to do something like this

[gallium-gonzollium]

We know why we’re all here, to celebrate Derek’s fantastic achievement of a 100m video. Props to you for becoming one of the biggest science youtubers ever, you deserve it and am always impressed by the level of work you and your team put in with each video! Really hope to see what’s to come and again, congratulations! -galliums

[Adan]

It took me 4 years and a community post from Derek that is super close to 100 million views and i wanted to support him so i finally gave in and watched it. You win YouTube. I can remove it from my watch later now

[PrimeSuperboy]

The dude that explained how all of this worked had such an infectious energy. He absolutely was waiting a long time to talk to someone about shade balls and couldn't contain his excitement.

[PostMoveClarity]

I wanna start my own reservoir but I don't have the balls to do that.

[EDWARD_KOENIG_ARCHITECT]

Love that executive. He loves his job and explains these shade balls like it's his life.

[seasonalserotonin]

I love how pumped the guy was while explaining the shade balls. Man loves his job.

[lukefilkins]

We all know their real purpose... to stop Mr. Incredible.

[TheOneWhoSometimesSaysOk]

US marine after returning to home to meet his kids after they were born: 0:57

[Ninjaman]

I remember getting a signed one of these in the mail. Can't believe it's been 5 years

[PopeLando]

I'm a truck driver, and getting to open a container and let a million plastic balls fall out and roll down a slope into a reservoir would definitely be the most fun delivery I would ever get to do. A career high, I tell ya!

[motorspeed]

That's the nicest, enthusiastic and knowledgeable Executive i've seen in a company.

[domkaz]

Congrats Vertasium! You are worth every single view you get and much more!

[spectre]

Bromate. How can such a friendly sounding chemical be so deadly.

[くらく]

Congratulations on your first 100M Veritasium. 👏🏻🎉

[sharkyn]

The first 100M video! Thank you for doing all the things that you, Derek, share with us. You made huge and small changes to each and every of our lifes. And in the end, a lot of videos have 42-nd element in them - Veritasium - and we appreciate that :)

[polt]

Alright I finally watched it youtube are you happy?!

[mrbob]

The fish in the water “who turn off the lights”

[xaproxiex]

Congrats man!!!! Your videos have always been super interesting to me and actually makes me want to learn more about things. You definitely deserve the 100 mill.

[Nope]

Congratulations on your 1st 100M video.
Here's to many more 🎉