Name: How Water Towers Work
Uploaded: 2022-12-16T14:58:11.000Z
Duration: 11 min
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Clean water is one of humanity's most fundamental needs, and those of us who live in urban areas

usually get our water from some kind of centralized public system.

Operating a water system is a major responsibility that has implications for public health and

In dense urban areas, a clean and abundant supply of water is an absolute necessity,

not just for drinking, but also for sanitation and firefighting.

And it's not just something we need every so often; water is a constant necessity both

day and night, on weekends, holidays, and any time in between.

So, the job of finding enough water, making it safe to use, and then reliably distributing

it to the system customers with almost no downtime is a monumental task that requires

And probably the most visible component of a public water system is the elevated storage

I'm Grady and this is Public Works, my video series on infrastructure and the humanmade

Let's say you're the owner of a public water system.

You've found a source of water of sufficient quantity for your customers, you've found

a way to clean that water so it's safe for them to use, and now it's time to send the

There are a few ways we can get water from one place to another.

Whether it's on the back of an animal, on a truck, or a bottle in your backpack, we

still physically carry water all the time.

But it's usually not the most efficient way.

The first infrastructure dedicated to water conveyance was the open channel.

Whether in a ditch, canal, or aqueduct, the water is carried by gravity, sometimes over

We still use open channels to carry water for irrigation and drainage, but they have

The water is exposed to pollution and contamination, channels bisect the land, making it difficult

to get across, and the water can only flow to areas of lower elevation than where it

And that last one is a big disadvantage, especially if you're trying to deliver water to an

So most public water systems today rely on pipes for distribution.

Simply putting a top on an open channel allows us to take advantage of pressure to move fluids

Just like electrons in a wire flow from high to low voltage, a fluid in a pipe will flow

So, if you raise the pressure at one end of a pipe, you can send your clean water to anywhere

And how do you raise the pressure of water?

In some cases a pump literally lifts the fluid to a higher elevation, but in most cases a

pump imparts energy to a fluid by raising its pressure.

And pumps, especially the size of pumps that serve entire cities, are expensive.

So if you're tasked with choosing the size of the pump you need for your public water

Maybe you measure the amount of water that the city uses in a given day and select a

It's midnight in your city and most of your water customers are asleep.

Besides the industrial customers that run 24/7, water demands are minimal, and your

But around 5 am, automated sprinkler systems start kicking in.

Around 6 am, people start waking up, taking showers, brushing their teeth, cooking breakfast,

It doesn't take long before the water demand exceeds the capacity of your pump.

Almost right off the bat, your new pump can't meet your system demand, because it was only

Water demand in large urban areas can vary significantly over the course of a normal

day, with the peak hourly demand (usually in the morning or evening) sometimes being

as much as 5 times the average daily demand.

So, if you are trying to meet your customer's water needs using just pumps, instead of just

one, you might need as many as five pumps (or one huge pump that can do the work of

And not only that, you'll have to be constantly cycling the pumps on and off to meet the variable

demand, increasing the wear and tear on your equipment.

Let's add a water tower to the system and try this experiment again.

It's midnight and demand is low, but your pump is running full wide open.

Instead of water flowing customers, it's flowing into your water tower, filling the

As morning comes and demand starts to increase, your pump continues running.

It's not able to meet the demand on its own, but the stored water in the tank is making

All your customers are getting the water they need.

As people start their day, demand again drops below average.

But, the pump keeps running and the extra flow goes into the tank.

Demand again begins to spike as the residents of the city start cooking dinner, taking baths,

All this extra water use drains the tank again before most people go to bed and the cycle

It's pretty easy to see how storage makes your water system more efficient.

It smooths out the peaks and valleys of water demand not just on your pumps but all your

upstream infrastructure, including your water treatment plant and raw water supply.

Without storage, all those facilities would need to be sized for peak demand, increasing

With enough storage, pumps and other infrastructure can be sized for average demands, saving not

only cost, but also complexity, because you don't have to predict changes in demand

Sometimes those peaks and valleys are predictable, but sometimes they're not.

Some of the biggest water demands in urban areas are from fires.

Without a firefighting force and enough water to supply them, fires can burn out of control

In fact, many of the deadliest disasters in history were fires in cities before modern

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How Water Towers Work

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