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

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Why Are 96,000,000 Black Balls on This Reservoir? 5
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

And from Kevin MacLeod "Marty Gots a Plan"

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

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

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💬 Comments on the video

Veritasium: It’s really rare to see 96 million of anything

Sand grains: Am I joke to you?

Author — Tiznado


"Are they safe for drinking water?"
***Drives through lake with a gasoline-powered motor***

Author — Beau Bernier


"It's very rare to see 96 million of anything"
PewDiePie: "hold my trebuchet"

Author — raveen mallawa


“Are they safe for drinking water?”

**powers a gasoline boat in drinking water**

Author — Joey Clemenza


It is so satisfying to see this. Looks like atoms on a large scale.

Author — Prakash Malathkar


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

Author — LukeFili


I love the taste of black moist balls in my drinking water

Author — MursunKulli


Him: Rarely do you see 96million of anything

Me: Sand

Author — Ejay Harding


"It's rare to see 96 million of anything"

jeff bezos: hold my stocks

Author — Sticky Note


5:52 the bird got smoked by that jet engine

Author — Hunter Pickering


That bald guy is super excited about his job and I love it.

Author — Noerdy


2019: got it recommend
2020: got it recommend

Author — YT Omni


"It's rare to see 96 million of anything"
Humans, atoms, cells, sand, nerves, snowflakes: am I a joke to you?

Author — Mr. Pichu


Most obvious question missed: How do you retrieve them after 10 years or whatever the lifespan is?

Author — jimclip


me: i wan-
brain: don't
me: i want to-
brain: *don't*
me: i want to drown in this

Author — Kianush


Jesus christ, I finally watched it youtube are you happy?!

Author — polt


5:51 the bird gets bamboozled but, look at the back of the engine. THE BLOOD OF THE BIRD SQUIRTS OUT 😓😓😓

Author — Little Teddybear


you are driving a boat in LA's drinking water, good work

Author — Shawn/IO


The look on that professor's face is priceless as he's explaining things; he's so happy when he's talking about such a niche thing that's awesome

Author — Sunny Gandhi


Poor bird shredded into dust. Who’s here after McGregor vs cowboy

Author — Bilal Rasuli