- So I dig water towers.
- Don't get me started on water towers.
- Oh really?
- Don't even.
- You like water towers too?
Or-- - I'm--
- Please, I don't wanna feel alone in this.
(laughing)
Please say yes.
(bright music)
- So when you talk about water towers,
- Yes.
- You have to be specific.
Because if you live in New York City,
- Right. - Water tower
means only one thing, and that's the vessel
that holds water on the top of your building.
But most people I think, when they hear water tower,
they think of the water tower that's in
the center of their town.
- [Interviewer] That's true.
- And if you came at the right time, in twilight,
and you're not quite fully there,
it looks like, they all almost look like
they landed from Mars.
- Right.
- Aliens comin' down.
In fact, during the broadcast of "War of the Worlds"
there are people thinking it's real
and they were described as having these,
you know, and so people were shooting water towers.
(whooshing) (clinking)
- [Interviewer] Shooting water towers.
- Yeah, thinking that was what was being described.
Anyhow, so--
- Kinda cool, actually.
(laughing)
- Water towers are interesting because
it gives you water pressure
without electricity, provided it's full of water.
- Right.
- All right? But how do you get the water up there?
You gotta pump it.
Water doesn't get there by itself.
- Okay, now--
- How you gonna get water up to the top of your roof?
You gotta pump it.
That takes electricity.
So here's what happens.
You pump the water up to the tower.
Oop, now that's a blackout.
You still have water until that tank empties.
- Right.
- Then you don't have water.
- 'Cause you have gravity.
As long as you have gravity--
- As long as you have, well, gravity to pull the water
from-- - To pull the water from--
the tower. - Then you have it.
- Right.
- So basically, if the electricity goes out,
quickly fill up everything with water.
And then it'll be gone and then you could,
you don't have to be stank, you know, the next day.
- So now here's the interesting question.
If you gotta pump the water up to the tower,
- Right.
- Why not just pump the water straight
to the people's apartments in the building?
- Oh, 'cause they might not need it in that moment.
Plus, you want enough water at any given instant
(water trickling)
to accommodate-- - To everybody.
- [Neil] If everybody wants to take a shower,
they can do it.
- [Interviewer] Right, because all the water is right
in this one tank. - Right in that one thing.
But if you, therefore, everybody would have to have
a pump, and what's the point of that?
- [Interviewer] Right.
- Right, right.
So it has that efficiency, okay?
- See, I like water towers even more now.
- Now here's another thing.
Have you ever noticed the buckles that go around
the water tower that holds theme together?
- Yes, they're like little metal rods that go
all the way round. - The metal rods.
Yeah, have you ever noticed those?
- Yes I have.
- Have you ever thought about them?
- Uh, not really.
- Let's split the water tower into three levels, right?
- Okay. - Top, middle and bottom.
- Okay, that would be a good three.
- So you can ask, what is the weight of the water
of that top third?
It's whatever it is, okay? - Right.
- [Neil] Call it 500 pounds.
- [Interviewer] 500 pounds.
- [Neil] So now I put a little buckle around that.
- [Interviewer] Right.
- [Neil] Okay? Right at that spot.
Let me go to the bottom of that.
Now what is the weight of water at that point?
Well, it's the top part-- - It's 500,
- Plus 500 - Plus 500.
- It's 1000 pounds. - It's 1000 pounds.
- Well if-- - Plus the 500 at the bottom
pushin' up. - I didn't get there yet.
I didn't get there yet. - Sorry.
- [Neil] So if one of these hoops is
the right strength to hold 500 pounds,
- [Interviewer] Right.
- [Neil] Then that one, I need more than one hoop
to hold it down here.
- [Interviewer] Right, yeah.
- [Neil] I need two.
- [Interviewer] Right.
- [Neil] If one can hold 500 and two will hold the thousand.
Now I'm at the bottom.
(water gurgling)
I have 500 plus 500, I got 1500 pounds
pressin' down the bottom.
- [Interviewer] Right.
- [Neil] I need three of those hoops.
- [Interviewer] Gotcha.
- Okay?
Go look at the water towers on the tops of buildings.
The hoops get closer and closer together--
- Closer and closer as you get to the bottom.
- As you get to the bottom.
Just because of this fact, the water gets heavy.
- Nice.
That is more than you ever wanted to know about water.
- I know, it is, it is so too much.
(laughing)
- And it's so cool as far as I'm concerned.
- If they're equally spaced, the person didn't know
what they were doing and you should not
move into that building.
Because the base of the water tower would not be
as structurally sound as the upper portions,
and that's, you know, that's where the stuff goes bad.
- You better have flood insurance if that happens.
(laughing)
Wow, that is so cool.
Water towers. - Water towers.
A little bit of physics.
- A little bit of physics.
- A little bit electricity.
- It's all happenin'.
- Oh, one last thing, one last thing.
- Oh, cool.
- If a building in Manhattan is lower than
about six stories, it doesn't need a water tower.
- All right.
Hm, because, wait, let me guess.
Because you can get the water to every apartment
just through the regular pressure of a pump?
- Yes, no, it's not a pump.
- Not a pump.
- It's the height of the reservoir that's
feeding Manhattan has that elevation above Manhattan.
- [Interviewer] Gotcha. So the pressure
is already there. - So the water falls.
The water falls from the reservoir
into your faucet. - Into your faucet.
- Over that height.
And you know something?
The ancient Romans knew that.
The aqueducts. - Aqueducts were
built on that.
- Aqueducts, some of which,
pieces of which are still standing,
- [Interviewer] Yeah.
- Was a channel that fed a lake,
or whatever was their water supply,
which was at a higher elevation than Rome.
And they scoop up that water and the water
just goes down all by itself. - By itself.
- No pump necessary.
- Boy, they don't build those aqueducts
like they used to.
- I know, and it's still standing.
- Yep. - We got stuff
here fallin' down that built 10 years ago.
And that's up for 2000 years.
- God dag.
- That just meant the mayor
- Of Rome. - Of Rome.
Spent too much money building it.
(laughing)
If your structures outlive your civilization
by 2000 years?
- Yeah.
- You overbuilt.
- You probably overbuilt.
That's very funny.
All right, there you go.
Who knew there was so much to learn
about water towers?
So next time I wash my hands, I'm gonna remember
how far that water had to travel
into my building.
Yes, right.
By the way, I never wash my hands.
Okay, if you're interested in learning more
about hydrostatic pressure,
why our everyday appliances are constructed
in certain ways, or how we use gravity
to our advantage every single day,
you should check out Brilliant.
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or, well of course, that's superpowers,
or a life long learner, or just somebody who
is naturally curious,
- Or if you're weirdly into water towers
like he is.
- Brilliant will help you master concepts
in math, science, and engineering through
solving fun, challenging problems.
I'm looking through the Outside the Box Geometry course.
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This is seriously amazing stuff.
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the first 78 that go to Brilliant.org/startalk--
- [Neil] Where'd you pull that number out of?
You know what? Thin air!
Right there.
You'll get 20% off an annual subscription
which helps you think like a scientist.
- You know where I pull numbers out of?
- Where?
- Thin space.
- Ooh, snap, he's-- - That's thinner
than your thin air.
- 'Cause there's no atmosphere.
You know what I mean?
He pulls his number, they go forever.
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(bright music)