Well Well Well

those reasons. However, one of the things, a very localized thing that hit my neighborhood in Atlanta was a massive water main break. It actually happened along the border of the Georgia Tech Campus, which is, by the way, not close to where I live, but it is in the city. And that break meant that thousands of homes, including mine, lost water pressure, and it took quite a while before water pressure was restored, and even then we were all

on a boil water advisory for several days. So in this episode, I thought maybe we could talk about the different technologies we use to supply homes with water, from personal or community wells to large municipal systems and why that boil water advisory was necessary in the first place, and we'll get to all of that. It's a lot of interesting tech and and ways that we have come up with clever solutions to the issue of getting water to people. Let's begin with just some basic facts about water.

This is like elementary school level stuff. So on our planet, it's the only stuff you can find occurring naturally in three of the four states of matter that would be solid or ice, liquid you know, water and gas or water vapor. You don't tend to find it occurring as plasma, the fourth form. It's more dense as a liquid than it is when it is a solid, which is why ice will float in a glass of water. The Earth has a water cycle that is pretty much self contained.

You know, we aren't really losing water out to space beyond some relatively tiny amounts here and there in some very specific circumstances, like if we send water up with astronauts and some of that water gets vented out into space, yeah, that's gone. But the stuff that is here is staying here. The water cycle is one that I'm sure you're all

familiar with. Liquid water evaporates into water, vapor, which goes into the atmosphere where it will eventually condense and form into clouds, and at high enough concentrations with seed particles in those clouds, droplets will form until they're big and heavy enough to fall back to Earth as rain or snow. In addition liquid water, it can run across the land. This is called runoff and into the ground. This is called percolation and infiltration, and then eventually through the ground,

seeping down through the ground and becoming groundwater. Plants absorb water in the ground through their roots, and then water evaporates from the leaves of plants into the atmosphere, and you get the picture. The water is changing form and

it's changing place, but it's not leaving the planet. So when you hear about things like wasting water, well, it's not that the water is going away permanently, but it does mean that you are using up water that is very important, and it takes a lot of treatment to get that water back into a state where people can make safe use of it again, so really it's not so much of that water has gone away, as now we have to do a whole lot of stuff to

that water in order to use it. Again, about of all the water on Earth is in the oceans, and that's just plain inconvenient. Ocean water is extremely salty, so you can't drink it, you can't use it for irrigation unless you put it through a desalination process, which essentially means you're pulling the salt out of the water. But we'll get into that in some other episode because that's an entirely separate topic that requires a lot of discussion.

Plus I've I've kind of covered it in previous episodes anyway, but only three of the water on Earth is freshwater, and on some parts of the planet it's really hard to come by. Wars are fought over the stuff, which isn't a surprise because news flash, in case you weren't aware,

we need fresh water to survive. Generally speaking, the typical human body is six water, and some oregans are much higher in water content than others, like the lungs, which are about water, so we can only go a few days without water before we start to suffer some pretty awful effects like death. Water can also carry with it some dangerous stuff. Toxins can leach into water, so you

can have dissolved medals like lead. This has historically been an enormous problem and continues to be a challenge to this very day in the United States, a country that arguably should have solutions in place to deal with this sort of thing all the time. We've seen a crisis that started really in two thousand fourteen in Flint, Michigan.

I'll get back to that story at the end of this podcast, because it is an important crisis that should have been handled or should have never happened in the first place, and it's an example of a massive failure in leadership because we do have the technology to deal with this sort of stuff, so it comes down to administration and sadly money. Anyway, water, even fresh water, isn't

necessarily inherently safe to drink. Water can carry toxins and pathogens, and those can have a negative effect on us up to and including death depending on the situation, and so much of human history, particularly in the era of civilization, has had a focus on how to gather water, to store it, to distribute it, and how to treat it. Now, early on humans seem to have managed fairly well without

massive problems related to water contamination. Now and then it would happen but by and large, humans got pretty good at avoiding water that wasn't safe to drink. Our senses tell us things such as if the water smells bad or tastes bad, that means it probably is bad. And that brings up an interesting series of questions about how we developed those reactions and senses. I mean, when you encounter a bad smell, you know that it's a bad smell. But why do our brains interpret it as bad? Why

do we have that negative reaction? What makes one smell a good smell and another one a bad smell. But to be fair, those questions and answers are all outside the realm of tech stuff. I just find them fascinating. In the early eras of human history, we were hunter gatherers and nomads, and once we decided, you know, our feet were done itching, we wanted to set up shop

and settle down. New challenges came about, not just regarding access to clean, drinkable water, which got to be more complicated as humans started to create larger and larger settlements, but also what to do with the waste we were generating, like the waste water. Contaminating drinking water with waste is you know, gross, and a terrible problem to have. It

leads to awful outbreaks of illness. So humans had to start figure out how to deal with all this once they began to make permanent settlements and populations began to grow. One of the important early techniques for humans, one used to the present day, was all about digging a well. And this was, you know, important if you didn't have access immediately to some body of water like a lake or river or stream. But it's a pretty straightforward process.

So I'm gonna be quick about the whole well digging thing. So you got the ground right, and the ground is made up of dirt and rocks and dinosaur bones and zombies and you know that kind of stuff. The ground in most places tends to be porous and permeable to water. So as water falls as precipitation, you know, rain or snow, and then either just goes into the ground or melts and then goes into the ground. It moves down through

the soil and rocks. It takes up the space that is in between particles and continues because of gravity, to move downward. Now, some layers in the soil might be impermeable,

you know, the rocks are less porous. Maybe there's a level of clay which is not terribly permeable to water, so then water will start to saturate the layers that are higher up from that impermeable one, it can't go lower, so the water just kind of continues to accumulate and saturate the porous ground, and it has nowhere else to go.

It can't really seep lower down. So if you were to look at the ground in a cross section, the top layers of dirt and rock would have some water content, but not at a point where the ground is saturated. At that level, water is essentially being held onto particles through molecular attraction, and it's just kind of loosely held

to the surfaces of rock particles. But as you go lower, you would find a greater concentration of water as the rocky soil becomes saturated with the stuff, meaning all the porous surfaces are full of groundwater. The top layer of this saturated zone of rock is what we call the water table. It is the top level of the saturated zone.

It's the upper layer of groundwater. And if you find an area of groundwater that readily refills a hole, like if you were to dig a hole and you hit groundwater, you take the water out, and more water comes in. You have found an aquifer. Aquifers are store houses for water. Aquifers get refilled or recharged when precipitation hits the ground and water soaks into the soil and gradually makes its way down to this layer again, so it's constantly being refilled,

or maybe not constantly regularly being refilled. The water in a well will start at around the same level of the water table in general, So let's say that the water table is ten feet down from the ground surface. That means once you hit ten feet as you're digging

your well, you'll start to see water. You typically would dig further down than that so that you would have a reservoir of water, but if you were to remove water from the well, it would continuously refill to that you know, that same level ten feet down from the surface. So if you locate an aquifer and you dig down far enough and you you know, shore up the sides of your hole so that it doesn't collapse in on itself, then you've got yourself a well from which you can

draw water. Now, in the olden days, you would do that with like a rope in a bucket, you would lower the bucket down, fill it up in the water than the well, and then pull the bucket back out. And you do that on demand. These days we have pumps and filters and stuff, and I'll get into those more a bit later. And there's another case I should cover, because it is a really cool thing. Some aquifers are confined. Now. That means that these aquafers have layers of less porous

or impermeable rocks or soil, both below them and above them. So, in other words, the water you can think of the groundwater is flowing. It's flowing through the rocks and soil, and sometimes this water flows into areas where the layer above is impermeable. So the water didn't just seep straight down. It seeped in from some other place, flowed into an area where it no longer can move in an upward

direction as more water is coming in. So this water is actually under pressure, you know, like the song by Queen and David Bowie. But here's the things that water doesn't compress. If you put pressure on water, then that water is going to push outward in all directions. This makes it different from a gas. You know, gas has molecules where you can typically force them closer together, and through pressurization you can compress a gas. You can't do

that with water. Applying pressure to water we can do some pretty impressive things. That's what hydraulic systems are all about. But let's get back to confined aquifers. So, because this type of aquifer is under pressure and the water can't escape that confined space due to those non porous rock layers, if you drill a well down into that confined aquifer, it allows the water an escape route and that result

in what is called an artesian well. The water in an artesian well will rise above the water table line. Because there's pressure on that water, it's going to start to move up the well. Uh sometimes it will move all the way up the well and come out of the well entirely. So, if you've got yourself a confined aquifer and you dig a well down to it, the water can be under enough pressure underground to create a constant flow up and out of the well. There are

a lot of springs that are fed this way. They are pretty nifty, and there are a lot of people who have pipes that extend down into the ground, and there's no electric pump or anything working on those pipes. The pipes actually go down into a confined aquifer. So just opening up a valve allows that water and escape route, and the pressure from the ground itself is pushing the water out. And I also need to explain the difference

between a well and a cistern. A cistern a c I s t e r in is a collect system that collects rainwater rather than groundwater. So it's a container, and sometimes it's one that's actually buried in the ground, so that can potentially confuse you if you just were to see one. But it's just there to collect the runoff of rainwater that feeds in through rain showers, so it doesn't pull groundwater up. You're just collecting rainwater before it can go into the ground. So that's pretty straightforward.

Now I want to talk about the physics of getting water out of a well and up to us. There are a few ways to do this, and one is one I mentioned already, a purely mechanical method to lower a bucket down into the well and collect water and then pull the bucket back out. A lot of classic wells you know the kind of I think about when I think of the word well. Have a simple pulley system that allows you to lower a bucket down into the well chamber and fill it up and then pull

the bucket back out. Pulleys are one of the simplest of machines. A pulley is a wheel around which you wrap a hope or wire, and the pulley just changes the direction of the force you need to use to do work. So instead of pulling straight up, you could pull down. And typically pulling downward is easier to do than pulling straight up, So while you're still lifting the same amount of weight, it's easier work to do because

of the direction of the force you're applying. Now, if you add more pulleys to a system, you can actually create a mechanical advantage and that makes work easier. But that is outside this episode. But what about something like handpumps. You've likely seen this in movies or TV shows where there's a hand pump for water. Maybe you've seen pictures

of one, maybe you've even used one. They tend to look like a pipe that's sticking out of the ground and it has a spout on one side where the water comes out, and a pump handle on the other that you pump up and down. So you give the handle a few pumps and before long water starts coming out of the spout. How does that work? This all has to do with pressure and using the atmospheric pressure to do work for us. So let's remember again, we're

all under pressure. At sea level. We're under an atmosphere of pressure or about fourteen point seven pounds per square inch. That's how much the atmosphere is pressing down on us at sea level. If we can decrease the pressure that's in a tube sticking down into the ground into ground water, if we can reduce the air pressure inside that tube by introducing a vacuum, water will move up that tube

because it's an area of lower pressure. It helps if you think about the outside pressure, the atmospheric pressure as pushing down on the water, and the lower pressure is an escape route. So the water moves up the area of lower pressure. So we think of it as you know, sucking, but that's not really the case. Like like when you're drinking from a straw, it's not that you're using suction

to draw the water up directly. You're reducing the air pressure inside the straw, and the atmospheric pressure is forcing liquid to go up the straw as a result. So really to do this, all we need is a device that can lower the pressure inside a tube that extends down into the water in order to draw water up somehow. But how do you do that If the tube you have has a spout at the top right, if it's open, then you can't create a vacuum because you have an

open path to the atmosphere. In general, the secret is in a pair of valves and a piston that is inside the pump. So if you could use Superman's powers of X ray vision and look through a pump, you would see that the handle connects to a reciprocating piston. So this is a piston that moves up and down inside the pump. But the base of this piston wouldn't be like a solid fixed disc, you know, like the piston you would find in a car engine. Instead, it's

a disc that's actually on a hinge. It's a valve. So when you are forcing the piston downward, the disc flips up because the pressure you're you're encountering is pushing the disc up. The valve is open and the piston is allowed to go down the shaft of this pipe. When the piston starts moving up again, the disc flips closed because again the pressure causes this to happen, and that means that it is sealed everything that's underneath the piston. And as the piston draws up, it starts to create

a vacuum. It's it's lowering the pressure inside the pipe. So every time the piston comes up to the top of its stroke and starts to move down again, the valve opens and allows are to pass past it, and as it gets to the bottom, it closes and creates suction. It does this over and over and over again as it starts to draw water upward. Now at the other end of the pump leading down into the well, you have a second valve. This is called the foot valve.

This one's very important because I just mentioned that when the piston is going down, the piston valve opens. Well, if that were all, if that was the only valve in the system, then the water would just fall away because you've just you know, allowed the air pressure to equalize again. So the air pressure, the atmospheric pressure is no longer pushing water up the pipe. So this foot valve when the piston is coming down, is closed, so

it prevents water from going back down the pipe. And when the piston is moving up again, when the piston valve is closed, the foot valve opens, allowing access to the water that's in the well. So it's these two valves working together as the piston is moving up and down that create the ability for the atmospheric pressure to

push water down, pushing it up the pipe. So every time the piston completes its upward journey and switches direction, the piston valve opens, the foot valve closes, water moves into the pump. It can't flow back down into the well because then the foot valve closes. It keeps that water steady, maintains the vacuum that's in place below the valve, and then the piston valve opens, allowing the piston to travel back down into the water that has collected inside

the pump. Then, as the piston begins to change direction and move upward, the piston valve closes again that traps the water above it. It essentially is like a bucket, right, It has just trapped the water that had already entered into the pump and it lifts it as the piston moves up, So you essentially are using suction the same way you would drink out of a glass, and then at the very very end of it using kind of a bucket method to pull the water up to the spout.

It's pretty nifty. Now, when we come back, I'll talk about centrifugal pumps and then we'll move on to more complicated means of getting water to people. But first let's take a quick break. One thing I did not get to when I was talking about handpumps a bit earlier is that since it does work on decreasing the air pressure in a tube and then relying on atmospheric pressure to do some work and push the water up the tube, there's actually a limit to how far you can pump

water vertically. If you're depending on atmospheric pressure to force water up a vertical distance of pipe, you can lift water a maximum of ten point three meters, and that is assuming you've got a perfect vacuum and that your pump is at sea level, and you can ignore some other realities of physics like friction and stuff. In practical terms, it means that ten point three is something you're never going to achieve. It's going to be more like seven

to eight meters of vertical space. That's how far you can pump liquid. Because while this air pressure thing does work, you can't just get rid of the concept of gravity. Water has weight to it. So let's say you've dug way down, like fifty feet down, and you finally hit the water table and you install a hand pump, and you pump that hand pump over and over again until you're ready to collapse, but no water is coming out.

So what's actually happening here. Well, while the pump lowers the air pressure in the pipe leading down to the well, and the atmospheric pressure is pushing against the water even as far down as fifty feet, it does cause water to move up the pipe, but that water still has weight, and eventually, with enough verticality there, you've got enough water. The weight of the column of water or ends up being equal to the force that the air pressure is applying to that water, and it's not going to go

any higher. Using this pumping method. It's kind of like a set of scales that achieves balance. Even if you could create a perfect vacuum, the water would not go as high as you need if it were fifty ft down. Centrifugal pumps work in a different way from hand pumps, but ultimately we'll have to deal with the same limitations of physics. So with a centrifugal pump, you've got a pipe that leads down into the water. This is where water will enter the pump from the well, and it's

called an inlet. It's pretty clever, right. There is a valve at the end of that pipe that sits inside the well itself, so it's submerged in the well water. This is the foot valve. It allows the water to flow into the pipe, but prevents it from flowing back out again. That is going to be important in order to make this whole system work. So when the pump is on, the valve opens and the water can flow

from the well into the inlet. When the pump is off, the valve closes and prevents any water that's already in the pipe and the pump from draining back out again. There's also a pipe that leads out from the pump. This is where the water will flow out while you're pumping it. It's the outlet and discharge nozzle. This is the part of the pump that leads into the plumbing system of a house. The heart of the pump is a circular or really actually a spiral shaped chamber called

the volute casing. And a volute is a spiral shape. It increases in size as you go around. And so a volute casing looks a little bit like kind of like a conk shell. And there's an electric motor that connects to a rotating shaft, and that shaft connects to a device called an impeller, and that sits inside the volute chamber. And impeller is designed to move fluid. And it looks kind of like a water wheel in that it is sort of wheel shaped, and it has these

sort of curved fins. They're actually called veins V A, N E S. And these veins push water. As the impeller rotates in a single direction, it forces water to follow the rotating path. As also an interesting note here, the curve fins look kind of like scoops, so you might first think they are scooping water, that they're forcing water out kind of like a paddle and pushing water

that way, but in fact that's not what's happening. The rotating impeller is creating friction to cause a rotational motion with the water, throwing it outward toward the edges of the volute chamber. So the water is following the smoothest path, and the fins actually curve away from the motion of rotation, not towards the motion of rotation, so there's no scooping going on with these things. So the water comes in

through the inlet towards the center of the impeller. It comes, you know, kind of head on to the impeller, and the motorized impeller pushes the water to the edge of the volute casing through centrifugal force. The water in the casing follows the curve of the spiral outward, so it hits the wall and then just starts to move along with the rotational force moving outward. The pressure increases as a result of this, will get more into pressure in a little bit and that eventually goes to the outlet

from the far end of the volute casing. There's also usually a cut off that prevents the water from just circulating in the casing over and over again. The diameter of the impeller and the speed of the impeller's rotation and the density of the fluid, because you know, these centrifugal pumps are used to move all sorts of fluids around, not just water. That determines how much force the pump is imparting to whatever fluid it happens to be pumping.

This process creates the lower pressure inside the pipe, and so while the centrifugal pump looks a lot different from a hand pump, it's ultimately relying on the same force to do a lot of the work that atmospheric pressure on the water that's in the well. But the centrifugal pump doesn't have the dual valve system that the hand pumps have. So getting one going means that first you have to prime the pump, and that means submerging the entire system from the pump all the way down into

the well with water. So you've got to make sure that there's water going through the pump all the way down the line into the well before the pump can start to pull water in. Uh. This is so that it can create that vacuum for the lower pressure for atmosphere pressure to push water. You know, to continuously feed the pump and uh that valve at the foot of the inlet pipe is what keeps the water from flowing out into the well while you're trying to get this

to work. And if the supply of water to the volut casing begins to diminish, you might introduce air bubbles, and that is bad news. The air bubbles that can travel to the impeller, they can collapse its speeds faster than sound, and those implosions can damage the impeller. This is called cavitation. It's really bad news for pumps. Similar to the centrifugal pump is the jet pump. The jet pump also uses an impeller, but otherwise it's a little

bit different in design. The impeller moves water called drive water through a path in the pump that loops back to point at the impeller. So UH, at the end of this loop, the path that leads back to the impeller, there's a narrow orifice, there's a jet and water can't be compressed, right, So if it can't be compressed to fit through this narrow path, then in order for the water to move through it actually has to pick up speed. As it picks up speed as velocity increases, pressure decreases.

This is kind of similar to if you have a a hose and you put your thumb over the end of the hose. You have UH increased the velocity of the water coming out, but you've actually decreased the pressure. But this whole process creates a vacuum that helps pull more water from the well are As we've pointed out, it doesn't really pull the water so much as it decreases the pressure, so atmospheric pressure does the job on the groundwater on the other side of the jet UH

is what is called a venturi tube. This is a tube that increases in diameter, so it gets bigger on the other side, and as diameter increases, the speed of the water will decrease, but the pressure of the water increases and the drive water and well water end up combining. They are at a high enough pressure to pump into the plumbing system. And this approach still is reliant on that atmospheric pressure, so again it only works down to

a certain depth. But what happens if the water in your area is at a lower level, If the water table is further down than what you can achieve by relying on atmospheric pressure well to pump water below that ten point three meters, and again that's the ideal that will never achieve. Engineers had to get really creative. There are two pipe systems that do this. One pipe is the inlet pipe. This is the one that will ultimately draw water from the well and supply it to the

house or building that you're using. And there is a foot valve at the end of this so again it prevents water from escaping once it enters the pipe. And this pipe goes all the way up to the pump that is on the ground. It's it's not buried or anything. It's right up there. And joining this pipe through a

special jet joint is a second pipe. This pipe comes from the pump, So the second pipe comes out of the pump, extend down into the ground to join the inlet pipe through this jet joint a little further up the pipe's length, and this joint is constructed so that the jet is moving water from this second pipe to shoot up the first pipe toward the direction of the pump. So the jet is down inside the well in this version of the pump, but the impeller is still up

at the pump on the ground. So what's happening is both these pipes and the pump are full of water. Okay, you've got a full system of water here. It's almost like a closed system. It's not really closed because you know, we have an outlet pipe with the pump, but let's

ignore that for now. When you turn on the pump, the motor begins to spend the impeller, and the impeller forces water down the second pipe, which then moves through this jet before joining up with the first pipe, and the water as it moves through the jet picks up velocity and it lowers the pressure. This lower pressure draws water from the well up the inlet, so this part is still using atmospheric pressure, but the whole assembly is down inside the well, so it's not lifting the water

very far. The drive water from the pump and the well water then pass through a venturi tube, and that increase in diameter decreases the water velocity but increases the water pressure. And it's that increase in water pressure that drives the water up further than it would go if we were just relying on atmospheric pressure to do the job. The high water pressure inside the tube moves the water up the inlet pipe into the pump and then ultimately

through the plumbing system. So this pump uses the trick of lowering pressure inside the pipe to draw up water to a certain elevation. Then, through increasing the water pressure inside the pipe, lifts it or pushes it further up to the pump. This system can work with wells that are much deeper than shallow ones, though the further down the water is, the less efficient the system will be. Finally,

we've got submersible pumps. Now, these are pumps that are actually in the water of the well itself, and rather than lifting water, they are pushing it up the pipe. They're also used for deeper wells. These pumps use a series of impellers that are separated by diffusers. Uh just

like the tubes we're talking about before. These lower the speed of the water, but they increase the water pressure further up the chain, and they do that by increasing the diameter of the pathway that the water is following. So the water moves through a series of impellers and diffusers over and over again, with the water pressure building along the way, and that ends up creating the pressure needed to deliver the water up the well and to

a home's plumbing system. One other common component of well systems know well water that is supplying homes is a pressure tank. Water from the pump will enter a pressure tank first before going through the home's plumbing system, and as water fills the tank, the pressure inside the tank increases. The pump has a sensor connected to this tank and there's a cut off value once a certain level of pressure is achieved, and at that point the pump shuts off.

So when you turn on a faucet in a house that's supplied with well water, the water actually first comes from the pressure tank and the pump will stay off unless the pressure in that tank dips below a certain threshold. At that point, the pump will kick on and begin to resupply the pressure tank with water. Now, the reason for the pressure tank is that it decreases the number of times the pump has to cycle on and off,

which helps cut down on wear and tear. There are usually some other components that are part of a well system, and these are meant to treat the water to remove stuff like minerals and organic material and sediment from your water. So a water softener is a type of device that does that. It's meant to treat so called hard water. Hard water contains high concentrations of minerals like magnesium and calcium. These are not toxic or anything like that, but they

can deposit minerals on stuff like on shower tiles. For example, I actually have some issues with hard water at my house, so I have to scrub my tubs and sinks and showers fairly frequently to prevent build up. Water softeners combine a tank filled with resin beads and a brian tank that you typically have to fill with potassium chloride pellets

or salt pellets on occasion. So incoming water moves through these resin beads, and the resin beads carry a negative charge and attract positively charged minerals that are in the water. So the minerals deposit to these you know, resin beats. They stick to the resin beads, and it allows the neutral y charged water to flow through and enter your plumbing. Now, eventually the beads attract enough minerals that the software needs to be quote unquote regenerated, at which point water flows

into the brine tank. It creates a brine, and then the brine moves through the softener tank. The salty water washes the mineral deposits off of the beads. The wastewater well then flush down a discharge pipe, and then the softerer tank is ready to go again, and you would have to occasionally refill the brine tank with pellets on a fairly regular basis. How regular would depend on how

much water you go through. There are other types of filtration systems that will remove specific metals and minerals and particulates from the water, like iron filtration systems. There's also systems that use ultraviolet light to kill off bacteria in the water. Actually technically doesn't so much kill off the bacteria as it renders the bacteria incapable of replicating. There are others that are designed to remove mercury, lead, nickel, other metals, as well as those designed to just filter

out sediment or or getting materials in general. When we come back, we'll move away from wells and talk about municipal water systems. But first let's take another quick break. Okay, so a well might supply a house or a small community with water, but what about big cities. These can sometimes share some you know, similar elements with well water systems, but due to scale, we do require a different approach. So you've got to look at the water systems for

cities as a group of stages and systems. First, you have to have a source for your water. Now, that could be an aquifer, it could be a lake, It could be a river or a stream or some combination of these. This water has to go through an extensive treatment process to remove anything harmful or unpleasant and make the water safe for consumption. More on that in a moment.

And then the treated water has to go through a water distribution system, so pipes and pumps that connect us to our water supply, including things like water mains, and that provides the water pressure needed to actually move water through the system and out our taps and showers and washing machines and whatnot. Then you've got a wastewater system.

I'm not going to really cover those in this episode, but the wastewater systems purposes to collect the used water and transport it to a wastewater water treatment facility which will remove as much contaminants from the wastewater as possible. You know, if we think of this a sewer water and that water should then be safe to return to the environment without contaminating stuff, you know, like your water supply. You don't want contaminated water to sink into the ground

and then become part of the groundwater. You've just major drinking water contaminated if you do that. There are also stormwater systems that are designed to channel rainwater or snow melt away from you know, streets and homes and stuff. These systems are integral to prevent flooding, and they move water away from the infrastructure of our cities and towns and move it back toward the environment like rivers and lakes.

That can also introduce contaminants. That's another issue, and again I'm not really gonna be able to go into that. I'm already running fairly along with this episode. So let's go through the process of water treatment. You've got your water source. So let's say in our example, it's a lake and you are transporting water from the lake to a water treatment facility. Let's say You've built massive pipes and pumps that pump water from the lake into a

water treatment plant. The first stage is called coagulation and flocculation. This is the first stage of removing stuff that we don't want in our water, like sediment, bacteria, and you know, other stuff that could be floating around in a lake, like you know, bits of wood or other organic materials. Incoming water from the lake will mix with chemicals like ferric chloride or aluminum sulfate, and these chemicals are called coagulants.

They will congeal with the suspended solids that are in the water, and it all comes down to again having an opposite charge. The coagulants have the opposite charge of the sediments, so they kind of bond to each other. They glom onto each other because those opposite charges are attracting one another. The mix of coagulants and water then moves into what are called flocculation basins, which is what a pair of words I mean. Try it, Just say it,

floculation basin. It's it feels great. Here the water and coagulants mixed together. Slowly, the coagulants begin to kind of glom onto each other and grow larger. Through this process, they form what are called flock particles. Essentially, they're beginning to just kind of you know, concentrate, and eventually, once a certain quality of water is reached, this mixture will move into another section, which could take one of two

different forms. So one of those forms is as sedimentation basin, and in fact, the sedimentation process is kind of what we call this part of the whole system. The purpose of this basin is to allow those flock particles to sink down to the bottom of this vessel, and they kind of form a nasty sludge. That sledge is removed from the tanks through special pipes near the bottom and then dumped in a landfill or something along those lines.

The water at the top of the sedimentation basin is the cleanest, so the closer yard to the surface, the cleaner the water, and that water is allowed to move over to the next phase. And in this version we would take water from the top. Now, the reason I say that is to contrast it with the alternative method, and that is called a floatation basin, a dissolved air floatation basin. So here you pipe air into the bottom

of the tank. You have like little pipes with holes in it, and you shoot air through those pipes and the holes allow bubbles to come in through the tank. Those bubbles flow up through the tank to go to the surface and along the way they push the flock particles up to the top of the tank and then you can use a sweeping arm to kind of gather

those flock particles together for collection. So in this version, the cleanness water is actually at the bottom of the tank, not the top, so we would have a pipe towards the bottom of the tank that we would draw water from to go into the next part of the system. Either way, the water coming out of this part of the phase will then go through a series of weirs or w e I R s. That's a type of low dam and it's really just meant to change the

flow characteristics of water. The water then moves on to filtration. Here the water will enter into a basin that has a sand filter in it. And the sand filter is exactly what it sounds like. It's a filter that's made up of different grades of sand. You have very fine sand, then you have medium, and you have really coarse sand. And wherever the water is coming in from, it's going to hit the course sand first and then move through

progressively finer grains of sand. You can have versions where the sand filter is fed through the bottom, so you're forcing water in through the bottom, it hits the coarse sand, and then the continuing force of water is pushing water further up through the filter. Or you can do it the other way, where water is coming in through the top, hits the coarse sand, and then filters down through it.

Most sand filters tend to take the bottom up approach, so we would just keep forcing water in and the water would move up through these different grains of sand. So how does it work. Well, it gets super technical, so stick with me. The particulates, the particles they're in the water, get caught on the sand as they encounter spaces where water can squeeze through, but the particles can't see.

I told you super technical. So yeah, the water continuously moves through areas of sand that are more and more densely packed together, and more and more of those particles are kept behind. Some water treatment plants will then pass that filtered water through a second filtration system where they'll use something like activated carbon, and the carbon particles are porous and they can capture smaller particles and bacteria and

remove that from the water. So if your fridge as a water filter built into it, it's likely using activated carbon to do the trick, the carbon grabs onto the particles and the water is free to go about its business. Then the water moves on to the next phase of the treatment system, which is disinfection. This is the phase that is intended to remove any remaining bacteria to make certain that the water is safe for human consumption. There are a few different methods in order to do this.

One of them is used a chlorine based compound. This is a really common approach in the United States. One is to use an ozone treatment, and then the third is to use UV light treatment, and some facilities use a combination of these. All three have different pros and cons Chlorine, for example, can continue to kill bacteria even after it's moved out of the water treatment facility because

there's still some chlorine in the water. So that means that this particular type of treated water can kill bacteria that gets introduced to the system after water has left the treatment plant. So if there's any point in the system where water from the outside environment can seep in, that chlorine can help take care of any bacteria that's

in that water. The other two versions of of disinfection don't allow for treatment of water once it's left the treatment plant, but they have their own os and cons. Now at this stage the water should be safe to drink, assuming everything at the water plant is working properly, so

you've now reached drinkable water. Once it's gone through all these phases, then it gets pumped into the city's water system, which is a network of pipes that feed out to the various homes and buildings in the city, with other pumps along the way to keep the water pressure going. And the water pressure leaves the planted around a pressure of for d P s I, and that is to make sure of a few things. One that the water has enough pressure so it can be pumped up to

areas of higher elevation. And two there has to be a positive water pressure in the pipes. In other words, the water pressure in the pipes has to be strong enough so that the water is pressing outward on the pipes at all times, because that prevents any other water

from outside from seeping into the pipes. If there are any gaps or cracks along the way, the internal water pressure is strong enough to push that water out so it's not gonna it's not able to get in, and that's important because if water could get in while that water would be untreated, and you would have all the dangers that are associated with contaminated water sources all over again. It would have been as if the whole process you

just went through at the treatment facility didn't matter. So if there's an indication that's somewhere along the water system from the treatment plant to the homes or buildings where the water is being delivered, that pressure has dropped somewhere along that pathway, that's when you tend to get boil water advisories. The concern is that if water pressure is low enough, then external water might have entered the pipe system and so it could be untreated water and it

would be unsafe to drink. That's why you're told to boil your water. It's really to kill off any potential pathogens. Now, boiling water won't remove everything, so you might end up with water that has higher concentrations of stuff like iron. But the primary concern, the first line of concern, is about potentially deadly bacteria like E. Coli. One of the most common municipal water system components is the water tower.

Now you've likely seen lots of these. They are tall containers giant, giant containers that can hold a lot of water. So like your typical swimming pool holds something around the line of twenty tho gallons of water, the typical water tower can hold a million gallons. But usually a water tower is designed so it holds about a day's worth of water supply for the area that water tower services.

So these water towers are really tall. They often are put in places of higher elevation because they depend on gravity to do a lot of work. Each additional foot of height that you have a container of water at increases the water pressure by point four three pounds per square inch. So the taller the tower, the higher the water pressure. Lifting a volume of water to a high point builds up a lot of potential in gy and releasing the water and letting it fall converts that potential

energy into kinetic energy. But in a plumbing system in which you've got water filling up the system of pipes, the potential energy converts over into water pressure. So let's imagine you've got a water system in place for an unoccupied city. No one lives in the city, but you've got the water system set up, You've got the water tower filled up all the taps in the city are

turned off. It's a sealed system. Right now, the weight of the water in the water tower is creating some water pressure throughout the system even if the pumps aren't on. So you open up a tap that creates an escape for the water and the water will come out of the pipe. The water towers are really there to act in a way kind of similar to the way a

pressure tank works. With a house that has a well as its source of water, the water tower helps reduce the workload that the pumps in the system have to do. If we didn't have water towers in times where people were using a lot of water where demand is really high, then pumps would need to power up more. They would have to work harder to deliver water to meet that demand and to keep the system working. That requires more energy. It also results in more wear and tear on the pumps.

But by storing water and water tanks and water towers, then we can use that to help supplement the water that's being supplied by pumps. We can keep running the pumps at a consistent level, which reduces wear and tear and is more energy efficient, and then we supplement that with the water from the water towers, and at night, when water demand is usually pretty low, then special pumps can pump water back up into the water tanks to refill them so that we again have a full day

supply raid to go. At the beginning of this episode, I mentioned Flint, Michigan, and that the crisis that went on in the city's water supply. So what happened. Well back in two thousand eleven, Flint, Michigan was in a really tough spot financially. The city had been largely built around the automotive industry in the United States. In the nineteen sixties, the population of the city was around two hundred thousand people, but the automotive industry in the United

States went through a total tumultuous time. Foreign car companies were able to really compete fiercely in the market in the United States, and American companies ended up having some massive problems as a result, and a lot of that meant that businesses started to move out of certain areas like Flint. So by two thousand eleven, with the automotive industry largely absent from the city, Flint's population was less

than half of what it had been in the nineteen sixties. Now, that also meant that the city was taking in less money in the form of taxes. Not only was the local economy suffering because of the failure of the automotive industry there, the city's coffers were empty, and the city

was actually in debt. In an effort to deal with this financial emergency, the city appointed managers who could make drastic cost cutting measures without going through the typical political processes, so they didn't have to seek after approvals, which sped things up considerably. The idea being that it was important to be expedient here. So one of the expenses that they identified was the water supply. Flint had been buying water service from Detroit. Detroit was processing the water and

then sending it on to Flint, Michigan. So instead Flint wood, for at least a short time, starting in two thousand fourteen, draw water from the Flint River while building out its own regional water system with the goal of pulling water from Lake Huron, which was the same source as what Detroit was using. But the water coming out the Flint River was really contaminated, and the treatment system that Flint was using was not capable of treating the water properly.

And here's where we got a tragic dilemma, because people need water, but the water that was coming out of the Flints system was unsafe to drink, and that unsafe water got pumped into the city's system and to people's homes, and some regions got worse water than others, and it was all pretty nasty stuff. You can actually watch videos of people turning on faucets filling up a clear glass,

and you can see that the water is discolored. But apart from looking and reportedly smelling bad, it carried with it lots of contaminants, including dissolved lead. Lead is incredibly toxic. There is no level of lead that is considered safe,

and consuming lead can lead to lifelong health problems. For a year, the city denied that there were elevated levels of lead in city water, claiming that any specific cases where people detected higher levels of lead, we're just restricted to the plumbing of those specific buildings or houses, saying, oh, it's not a it's not a systemic problem. It's a problem with your plumbing. And it took an outside investigation

that proved otherwise. It said, no, this is a city level problem, and it means that people have been relying on a water system that was contaminated for a full year. Now, in two thousand fifteen, under immense pressure, Flint switched back to using water from Detroit, but by then a lot of damage had already been done. Now you'll occasionally see the message of Flint, Michigan still doesn't have safe drinking water,

but that's actually not true. The water in Flint, Michigan, is now as safe or safer than other cities in the United States. However, the amount of damage that was done during the switch to the Flint River remains a problem, and for many residents it could be a problem that they have to manage for the rest of their lives.

So that explains the challenges associated with delivering water to people now in our civilized age, is still a massive undertaking and obviously if something goes wrong, it could have dire consequences. And it reminds us that we have to be very careful with our water supplies. Even with the water treatment systems that we have, we need to be careful. It is easy to contaminate a water supply, whether that

is a river or a lake or even groundwater. If you have poor wastewater treatment plans, then that wastewater can seep into the ground and then you've got very dangerous bacteria and other contaminants in the water system that could then be consumed later on. And that's why this is so important, and the technology involved is pretty interesting stuff.

I highly recommend watching videos. I know that trying to visualize something like a centrifugal pump as a little tricky, but there's some great videos on YouTube that really show you how it works in case you want to get a visual on it. These things are really super cool, and again, the harnessing of physics is something I always

find really fascinating. If you guys have any suggestions for future topics of tech stuff, whether it's a technology or a trend, into or a company or whatever something related to tech, send me a message and tell me about it. You can send it on Twitter. The handle for the show is tech Stuff H s W and I'll talk to you again really soon. Text Stuff is an I

Heart Radio production. For more podcasts from I Heart Radio, visit the I Heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.