Chlorine in drinking water and its health effects

Alright, so I just got back from a run and I was absolutely parched, so I basically chugged a ton of tap water. Now I feel like some kind of weird yellowish-green gas is actually evaporating right out of my skin 😱 What should I do? Is this that chlorine in the city water everyone keeps talking about? 😁

feralwolf24 said::-))))))). Sure, obviously. Granules :-))) And at every treatment plant, you just find Joe standing there with a shovel, tossing in handfuls of granules :-))))

That’s right, you add the granules. And honestly, there isn't any John, Harold, or Solomon to be found around here either. 😁 Don't we all know that there are automated stations out there specifically designed to inject chlorine?
I am going to say this one more time because clearly, there is some fundamental misunderstanding happening here: residual chlorine is not used to disinfect pipes or tubing. Once you detect residual chlorine, it serves as a signal that the disinfection process is already complete and adding more is entirely unnecessary. Is it really that difficult to grasp? Before any piping is ever put into service, it undergoes a rigorous disinfection using 20 to 30 milligrams of chlorine, held for a full 24 hours, followed by a thorough cleaning before the lines are finally connected to the main water grid.
If you happen to be sitting on some secret, magic-bullet method for the water disinfection process that hasn't even crossed the radar of the industry experts yet, please, do me a favor and share it? My professor and I are all ears, and we would be more than happy to turn that little bit of insider knowledge into a serious payday. 😉😉😉

stormyheron4 said:Alright, so I just got back from a run and I was absolutely parched, so I basically chugged a ton of tap water. Now I feel like some kind of weird yellowish-green gas is actually evaporating right out of my skin 😱 What should I do? Is this that chlorine in the city water everyone keeps talking about? 😁

A little get-together for the crew😁

Susan Harris4 said:A little get-together for the crew😁

Awesome. Just make sure the main drink is that Clorox-treated water. 🙂

stormyheron4 said:Awesome. Just make sure the main drink is that Clorox-treated water. 🙂

That water hits you harder than a shot of cheap bourbon on an empty stomach. 😁😁

Susan Harris4 said:That’s right, you add the granules. And honestly, there isn't any John, Harold, or Solomon to be found around here either. 😁 Don't we all know that there are automated stations out there specifically designed to inject chlorine?
I am going to say this one more time because clearly, there is some fundamental misunderstanding happening here: residual chlorine is not used to disinfect pipes or tubing. Once you detect residual chlorine, it serves as a signal that the disinfection process is already complete and adding more is entirely unnecessary. Is it really that difficult to grasp? Before any piping is ever put into service, it undergoes a rigorous disinfection using 20 to 30 milligrams of chlorine, held for a full 24 hours, followed by a thorough cleaning before the lines are finally connected to the main water grid.
If you happen to be sitting on some secret, magic-bullet method for the water disinfection process that hasn't even crossed the radar of the industry experts yet, please, do me a favor and share it? My professor and I are all ears, and we would be more than happy to turn that little bit of insider knowledge into a serious payday. 😉😉😉

Give my best to the professor :-))) Tell him you guys must have some kind of deal going on with those Japanese robotics companies then :-))) Otherwise, they'll be out there using shovels to toss it in whenever John isn't looking :-))) Seriously though, standard dosing stations can only handle liquid, not solids. Unless someone is out there with a shovel (which is slow) or a spoon (small amounts, but still), it won't work. It takes a good month for that stuff to dissolve, and let me tell you, it’s a real pain when it melts too slowly.
As for those pounds of residual chlorine you mentioned... what can I say? :-)) Anyway, give your prof a big hug for me :-)))

feralwolf24 said:Give my best to the professor :-))) Tell him you guys must have some kind of deal going on with those Japanese robotics companies then :-))) Otherwise, they'll be out there using shovels to toss it in whenever John isn't looking :-))) Seriously though, standard dosing stations can only handle liquid, not solids. Unless someone is out there with a shovel (which is slow) or a spoon (small amounts, but still), it won't work. It takes a good month for that stuff to dissolve, and let me tell you, it’s a real pain when it melts too slowly.
As for those pounds of residual chlorine you mentioned... what can I say? :-)) Anyway, give your prof a big hug for me :-)))

You clearly haven't a clue what you're talking about, so keep rambling... 😁 it's the classic behavior of a wannabe scientist. Why don't you actually go study how a US municipal water supply system functions before you try lecturing me again? 😉😉

feralwolf24 said:Thanks, Tyler Morgan3. Just a tiny correction here. Chlorine dioxide has some great marketing behind it, but you don't see it used everywhere. A lot of plants tried switching over, but it didn't really stick; many went back to standard chlorine or hypochlorite (which just turns back into chlorine anyway through disproportionation). The main reason people move away from chlorine dioxide so fast is how quickly it breaks down and the byproducts it leaves behind, like chlorates.
Regarding ozone, it's commonly used for oxidation. Around here, we mostly use it to get rid of iron or to oxidize Arsen to make it easier to remove, since you can't pull out Arsen in its 3+ form. A lot of places still use permanganate instead of ozone for that. Ozone is actually perfect for drinking water plants dealing with high organic matter, like humic or fulvic acids, because even small doses can help break those down. We have to be pretty careful with dosing since it's so unstable (we stay under 3 mg/L O3 here), especially since studies on how it affects water chemistry aren't fully settled yet.

I haven't a clue what the smaller water treatment plants are running, because honestly, it all comes down to volume and flow rates. On the massive municipal systems, they just use chlorine and its compounds, and frankly, it works fine. As for ozone? For our specific water, it’s basically overkill and a waste of money. Iron levels are tiny, so it usually just settles in the pipes (you see that sediment flushing out at the hydrants every once in a while). And arsenic? It's practically non-existent. Besides, As 3+ is super unstable anyway and flips to As 6+ pretty fast (thank God, because As 3+ is way more dangerous and toxic!). The real kicker, as far as I know, is that ozone doesn't actually kill off organic molecules entirely; it just shreds them into smaller fragments that hang out in the groundwater, settle, or react, so you're basically just spinning your wheels. Luckily, the American groundwater acts like a perfect natural filter, and we really need to protect it because the quality of our tap water depends entirely on keeping that underground stuff clean. We've got some of the healthiest water in the Western world (second only to Vienna) and we get it with hardly any processing at all!👍 The real question is whether we actually realize how lucky we are and if we even care enough to protect the treasure we've got!🙂

Susan Harris4 said:That’s right, you add the granules. And honestly, there isn't any John, Harold, or Solomon to be found around here either. 😁 Don't we all know that there are automated stations out there specifically designed to inject chlorine?
I am going to say this one more time because clearly, there is some fundamental misunderstanding happening here: residual chlorine is not used to disinfect pipes or tubing. Once you detect residual chlorine, it serves as a signal that the disinfection process is already complete and adding more is entirely unnecessary. Is it really that difficult to grasp? Before any piping is ever put into service, it undergoes a rigorous disinfection using 20 to 30 milligrams of chlorine, held for a full 24 hours, followed by a thorough cleaning before the lines are finally connected to the main water grid.
If you happen to be sitting on some secret, magic-bullet method for the water disinfection process that hasn't even crossed the radar of the industry experts yet, please, do me a favor and share it? My professor and I are all ears, and we would be more than happy to turn that little bit of insider knowledge into a serious payday. 😉😉😉

No, they don't just dump in granules. Seeing residual Cl is just proof that the disinfection worked and that the water usage is steady enough that it isn't just sitting stagnant. It happens all the time where you'll check the nearest hydrant near your house and see, say, 20 ppb of residual Cl, but when you turn on your tap, there’s none left! What do you think happened to it (especially if you haven't been home for a while)?
And as for just flipping a switch to put a pipeline into service? It's not that simple or fast. You're seriously mistaken here (regardless of what you and your professor think...).🙂

Tyler Morgan3 said:I haven't a clue what the smaller water treatment plants are running, because honestly, it all comes down to volume and flow rates. On the massive municipal systems, they just use chlorine and its compounds, and frankly, it works fine. As for ozone? For our specific water, it’s basically overkill and a waste of money. Iron levels are tiny, so it usually just settles in the pipes (you see that sediment flushing out at the hydrants every once in a while). And arsenic? It's practically non-existent. Besides, As 3+ is super unstable anyway and flips to As 6+ pretty fast (thank God, because As 3+ is way more dangerous and toxic!). The real kicker, as far as I know, is that ozone doesn't actually kill off organic molecules entirely; it just shreds them into smaller fragments that hang out in the groundwater, settle, or react, so you're basically just spinning your wheels. Luckily, the American groundwater acts like a perfect natural filter, and we really need to protect it because the quality of our tap water depends entirely on keeping that underground stuff clean. We've got some of the healthiest water in the Western world (second only to Vienna) and we get it with hardly any processing at all!👍 The real question is whether we actually realize how lucky we are and if we even care enough to protect the treasure we've got!🙂

Yeah, chlorine is definitely used—specifically sodium hypochlorite, which at 13% active chlorine is a pretty intense concentration. Around here, we don't really use ozone for basic disinfection; it’s mostly reserved for oxidation if the system is dealing with arsenic, iron, or organic matter. Potassium permanganate is also used for that same purpose. In the Midwest, the most common groundwater profile involves iron, manganese, and ammonia paired with organic matter, plus arsenic specifically tied to arsenite soil. You can strip those out quite easily and efficiently using biological sand filters (though you'll see plenty of people selling "special" catalytic mixtures that are basically just a tax on fools). Since iron comes from underground where oxygen levels are zero, it shows up as 2+, which makes it a pain to remove. We have to oxidize it to 3+ so it becomes bulky, forms hydroxides, and settles out either in sedimentation tanks or on the biofilter—which is why we usually put anthracite at the top of the filter. Iron oxidizes pretty easily just by being exposed to air. If there's arsenic present, you need a stronger oxidizing agent than just oxygen, like KMnO4 or O3. The ratio and makeup of arsenic vary wildly depending on the well. (By the way, you had a little typo there—you wrote 6+, but arsenic is inorganic and exists as 3+ or 5+). Removing As 3+ is nearly impossible; as you mentioned, it's much worse than 5+. Ion exchange, adsorption, coagulation, and flocculation just don't work on it, and nanofiltration membranes are way too expensive to use just for that. Ultrafiltration is a cheaper alternative, but it only works if you can get the arsenic into its 5+ form first. Manganese and ammonia are handled biologically, which is actually very effective and inexpensive. Iron concentrations can get pretty high, and you definitely don't want iron, manganese, or any other metals settling in the pipes. Those deposits create perfect breeding grounds for microbes, and once oxygen-rich water flows through them, you've got a party. Of course, to prevent that kind of buildup, you absolutely need residual chlorine to make it all the way to the end of the line and reach the last consumer in town. Regarding organic matter, it's true that it breaks down into H2O and CO2, but honestly, you're right—most of it just ends up as shorter chains. That's where chlorine gets tricky. When it reacts with organic compounds, it can create some pretty nasty byproducts called trihalomethanes (everyone knows chloroform). They're especially unpleasant because, even though they evaporate easily, they diffuse through the skin quite readily. This means you actually get the highest exposure when showering with that water. We dealt with a similar issue in a small town outside of Chicago due to high organic matter, but they've since fixed it.

My arm is killing me, but look, there’s a lot of complex interplay and dependency involved here. It isn't just a simple fix. You really have to understand the exact makeup of the water and its chemistry—which reactions have a stronger affinity, the specific order in which they occur, and all that good stuff.

And regarding that last point you made, it’s honestly pretty sad how many people around us are completely oblivious to it. :-((

Susan Harris4 said:You clearly haven't a clue what you're talking about, so keep rambling... 😁 it's the classic behavior of a wannabe scientist. Why don't you actually go study how a US municipal water supply system functions before you try lecturing me again? 😉😉

Oh, my dear Angel :-))), I am so sorry if I shattered your little illusion regarding water and the municipal supply system. If that’s enough to get under your skin, by all means, keep believing you have all the answers. That's basically how this whole country runs anyway—just packed with "experts" in every single field, all steering us blindly toward whatever comes next, led by these great professionals.

feralwolf24 said:Oh, my dear Angel :-))), I am so sorry if I shattered your little illusion regarding water and the municipal supply system. If that’s enough to get under your skin, by all means, keep believing you have all the answers. That's basically how this whole country runs anyway—just packed with "experts" in every single field, all steering us blindly toward whatever comes next, led by these great professionals.

Thank God we have you, the one shining beacon of clarity on the American horizon! 😁

Tyler Morgan3 said:No, they don't just dump in granules. Seeing residual Cl is just proof that the disinfection worked and that the water usage is steady enough that it isn't just sitting stagnant. It happens all the time where you'll check the nearest hydrant near your house and see, say, 20 ppb of residual Cl, but when you turn on your tap, there’s none left! What do you think happened to it (especially if you haven't been home for a while)?
And as for just flipping a switch to put a pipeline into service? It's not that simple or fast. You're seriously mistaken here (regardless of what you and your professor think...).🙂

???

Look, this whole business regarding the pipeline is far more complex than you're making it out to be; why don't you try asking any major utility company? (If you happen to know a large-scale US municipality, feel free to name one.)

While sedimentation and filtration processes go a long way toward cutting down the microbial load in our water supply, does that really mean we can stop worrying? Not exactly. While these steps significantly reduce the number of microorganisms present, they don't provide a complete guarantee of safety on their own. It’s a common misconception to think that if the water looks clear after passing through a filter, the job is done. But how many microscopic threats are still lurking just beneath the surface, waiting for the right conditions to multiply? We have to remember that filtration is just one stage in a much larger, more complex chain of events designed to ensure what comes out of our taps is actually safe to drink.
So, what you're saying is they've been completely wiped out.
To get rid of them, you have to go through the standard water disinfection process.
It doesn't actually achieve the total annihilation of every single living microorganism in the water, much like what you would see with true sterilization, does it?
Isn't the entire point of the water disinfection process to ensure that the water is actually safe from a bacteriological standpoint?
(securely).
So, if we're looking at what this assignment is actually getting at, the whole point of the water disinfection process is to wipe out infectious microorganisms, primarily.
When we start discussing intestinal bacteria and fecal matter, aren't we really talking about the fundamental reality of our biology? It’s a subject that many people find uncomfortable to address directly, yet it remains one of the most critical aspects of human health and sanitation. Is it not true that understanding these specific bacterial strains is the only way to truly grasp how our internal systems function—or fail?
Disinfection usually serves as the final stage in the water conditioning sequence—and in some cases, it might even be the only one used—but is that really enough to guarantee safety?
It’s mandatory.
When we look at the various methods used for the water disinfection process today, which ones actually stand out as the most widespread?
When we look at the reality of disinfecting water using chlorine and its various derivatives, aren't we essentially debating the fundamental mechanics of public health? It isn't just about pouring chemicals into a tank; it’s about understanding how these specific compounds interact with pathogens to ensure safety. Is there a more efficient way to manage large-scale sanitation, or are we simply stuck with these traditional methods because they work?
Is ozone disinfection actually worth the hype? When you look at the complexities of the water disinfection process, one has to wonder if we are overcomplicating things just for the sake of innovation. Is there any real evidence that this method holds up better than the standard approaches we've relied on for decades, or are we simply chasing a trend?
Is UV light disinfection actually worth the hype? We need to take a serious, measured look at using ultraviolet radiation for sterilization processes. Is it truly the gold standard we claim it to be, or are we just following a trend without questioning the underlying efficacy?
Chlorine disinfection and its various derivatives primarily serve to wipe out bacteria, though their utility extends much further than that, doesn't it?
When you consider how certain types of viruses and parasites operate alongside the oxidation of organic and inorganic matter, don't you have to wonder about the real impact on flavor profiles and overall quality? It’s all part of that complex interplay between biological contaminants and chemical breakdown.
Is anyone else dealing with these strange odors coming from their tap water? It makes you wonder if there’s actually something wrong with the local supply, or if it's just some minor issue with the pipes in my building. Is it normal for the water to smell like this, or should I be calling the city utility department to report a problem?
When it comes to modern water disinfection processes, this particular method is what you'll see being used most frequently in the field.
The bactericidal power of chlorine fundamentally relies on its ability to dismantle the specific enzymes responsible for converting starch into sugar, which essentially cripples the organism's metabolic functions. Is it not fascinating how such a simple chemical mechanism can effectively shut down an entire biological process?
They are absolutely essential if you want any kind of microorganism to actually survive.
When it comes to standard water disinfection processes, you'll most often see people relying on either gaseous chlorine or sodium hypochlorite, though calcium hypochlorite is also frequently in the mix.
Is there any reason why anyone would question the effectiveness of Clorox? It serves as an incredibly reliable disinfectant precisely because it delivers such immediate, decisive results in a remarkably short window of time.
While the costs remain within an acceptable range, one has to wonder if the trade-off is truly worth it, given that chlorine tends to leave the water with such an unpleasant odor.
The amount of chlorine required really comes down to the total organic and inorganic matter present in the water that needs oxidizing. Is there any other way to look at it? It all boils down to the specific indicator used.
What exactly constitutes a chlorine dose? It refers to the amount of unneutralized, or what we call "free" residual chlorine that remains lingering in the water after the initial reaction has taken place.
The oxidation of both organic and inorganic substances has been completed. Consequently, when evaluating the water disinfection process, one must consider how the chlorine dosage is actually applied.
The dosage keeps climbing steadily until that residual chlorine finally shows up in the chlorinated water—usually topping out at around 0.5 mg/L.
When you're looking at the standard water disinfection process for drinking water, you have to consider that a typical target dose for chlorine sits somewhere between 0.5 and 1.0 mg/L, provided you allow for a contact time of roughly 30 minutes. Is that enough to ensure safety, or does it leave too much to chance?
Ozone disinfection works by bubbling ozone—essentially oxygen-enriched air—directly through the water supply.
Following an electrical discharge that results in a triatomic structure—specifically O3.
How exactly is ozone produced? It’s done by passing a current of clean, dry air between two electrodes.
The potential difference ranges from somewhere between 10,000 and 20,000 volts. Because this specific form is inherently unstable, ozone doesn't stay in that state for long before it rapidly transitions into...
Oxygen—specifically O2, the oxygen atom being released during the process—acts as an incredibly potent oxidant when it comes into contact with protoplasm. Does anyone actually stop to consider the sheer intensity of that reaction?
When you consider the sheer volume of microorganisms floating around in our water supply, doesn't it make you wonder about the effectiveness of the standard water disinfection process? It’s one thing to talk about cleanliness, but it's quite another to actually tackle the microscopic threats that exist within the system. How exactly do we ensure that these organisms are neutralized before they reach our taps?
Ozone is an incredibly effective choice for the water disinfection process because it doesn't leave behind that nasty, chemical odor or any toxic residue. Is there really any reason to settle for anything less when you can have pure, clean water without the unpleasant side effects?
While the effectiveness of ozone systems is undeniable, we have to face the reality that the operational costs for running this kind of equipment remain prohibitively high in today's market. Is it really worth the investment when the overhead stays this inflated?
To achieve effective water disinfection, you really need to look at a dose of about 1 [mg l-1] of ozone, while also accounting for the specific contact time required between the ozone and the water.
The water flow is running at about five minutes.
Is it really that complicated to understand that UV water disinfection is essentially just the process of using ultraviolet light to wipe out bacteria in the water being exposed?
When you look at the mechanics of ultraviolet light, specifically within the 200 to 300 nanometer wavelength range, its ability to act as a bactericide becomes quite apparent. Is it any wonder that this specific spectrum is so effective at neutralizing pathogens?
The peak should be set at a maximum of 250 nm.
These bulbs are manufactured within glass envelopes under low pressure, containing mercury vapors. While they can reach a power output of up to 200 watts, one has to wonder if that level of intensity is truly necessary for every application?
We're looking at a lifespan somewhere in the neighborhood of 2,000 to 4,000 hours.
If you want a water disinfection process using UV light to actually work, doesn't the water have to be absolutely pristine and constantly circulating?
Is there anything more frustrating than spotting a single, stubborn speck of debris floating right in the middle of that thin layer of water?
The main advantage of this specific water disinfection process is that it’s relatively simple to operate without messing with the water's taste, but...
The fundamental flaw here lies in the fact that we aren't meeting the necessary threshold for advanced water conditioning beforehand. Is it really any surprise when the system fails to perform if the initial preparation is insufficient?

Pipe disinfection. Any brand-new or reconstructed water main network must undergo a full disinfection process before it can be put into service.
This is achieved by filling the sections with water containing a concentration of 20 to 30 [mg]
of chlorine per liter. The chlorination phase lasts for at least 24 [h], after which the entire water system is thoroughly flushed
with clean water

P.S. This is just a collection of lectures from a professor who has spent the last three decades designing water supply systems all across the USA.😁

Look, Susan Harris4, I could tell right away you were either a civil engineer or a mechanical engineer. I don't work on water supply systems myself, but I’ve been working in water treatment technology long enough alongside a guy—my boss—who I’m sure your professor would respect and value quite highly because he really knows his stuff. What I’m telling you comes from the chemistry side of things. How exactly a water main gets disinfected isn't my area, though I'm certain it happens. My point is, once you start using that pipeline for transport, it isn't going to stay sterile forever. That's the whole issue. I'm not trying to step on your toes professionally, so I'm not sure why you feel the need to lecture me on mine.

feralwolf24 said:Look, Susan Harris4, I could tell right away you were either a civil engineer or a mechanical engineer. I don't work on water supply systems myself, but I’ve been working in water treatment technology long enough alongside a guy—my boss—who I’m sure your professor would respect and value quite highly because he really knows his stuff. What I’m telling you comes from the chemistry side of things. How exactly a water main gets disinfected isn't my area, though I'm certain it happens. My point is, once you start using that pipeline for transport, it isn't going to stay sterile forever. That's the whole issue. I'm not trying to step on your toes professionally, so I'm not sure why you feel the need to lecture me on mine.

Where do you get off trying to lecture me on water supply procedures? Sure, you might know your chemistry, but you are miles away from what actually happens out in the field. Everything I’ve laid out here is based on practical, boots-on-the-ground reality, which is a world away from the laboratory where you play around and act like an expert!

p.s. You admit that disinfection happens, yet you have no clue how or why, so why are we even arguing?
Water mains are disinfected specifically to kill off coliform bacteria, but other types of bacteria can live there just fine—in fact, they thrive.

Which boss of yours are we talking about, and which professor of mine? 😁

Look, I really don't have the energy to go back and forth with you anymore. You’re talking about laying down pipes based on your field experience, while I’m talking about the treatment plants that process the water before it even enters those pipes—also based on my own field experience. Once you finish installing the line, you're basically done until some emergency requires a replacement. On our end, from the moment a well is drilled, we handle everything: sampling, quality control, monitoring, and developing pilot plant technology. We design systems we can guarantee will work reliably while staying affordable for the average American family. We draft the tech specs, oversee the builds by the construction or mechanical teams once they get their permits, and then we monitor the equipment and jump in whenever an emergency pops up. Just for context, my boss is a professor—the kind of guy who is essentially the gold standard for water authorities across the entire US. He's incredibly respected, though I’m just the one working alongside him. I don't claim to have half his expertise; I don't even have the ambition for it because, honestly, I just want to be home with my family.

Think whatever you want. Your job is disinfecting the lines; mine is managing the water itself. You handle the transport, I handle the substance. And as for "fieldwork"... let's not try to compare how many technical reports are filed at American water utilities under our respective names among all the others. It's just not happening. :-))

Susan Harris4 said:???

Look, this whole business regarding the pipeline is far more complex than you're making it out to be; why don't you try asking any major utility company? (If you happen to know a large-scale US municipality, feel free to name one.)

And which one would you even recommend to me?😉

Also, what are you on about? You honestly think water just sits perfectly still in those pipes without any issues? Or do you really believe chlorine isn't a solid indicator of how much water's being used? (Not that you'd know, since you totally butchered those numbers earlier).🥳